cfq-iosched.c revision 5624a4e445e2ec27582984b068d7bf7f127cee10
1/* 2 * CFQ, or complete fairness queueing, disk scheduler. 3 * 4 * Based on ideas from a previously unfinished io 5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli. 6 * 7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> 8 */ 9#include <linux/module.h> 10#include <linux/slab.h> 11#include <linux/blkdev.h> 12#include <linux/elevator.h> 13#include <linux/jiffies.h> 14#include <linux/rbtree.h> 15#include <linux/ioprio.h> 16#include <linux/blktrace_api.h> 17#include "cfq.h" 18 19/* 20 * tunables 21 */ 22/* max queue in one round of service */ 23static const int cfq_quantum = 8; 24static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; 25/* maximum backwards seek, in KiB */ 26static const int cfq_back_max = 16 * 1024; 27/* penalty of a backwards seek */ 28static const int cfq_back_penalty = 2; 29static const int cfq_slice_sync = HZ / 10; 30static int cfq_slice_async = HZ / 25; 31static const int cfq_slice_async_rq = 2; 32static int cfq_slice_idle = HZ / 125; 33static int cfq_group_idle = HZ / 125; 34static const int cfq_target_latency = HZ * 3/10; /* 300 ms */ 35static const int cfq_hist_divisor = 4; 36 37/* 38 * offset from end of service tree 39 */ 40#define CFQ_IDLE_DELAY (HZ / 5) 41 42/* 43 * below this threshold, we consider thinktime immediate 44 */ 45#define CFQ_MIN_TT (2) 46 47#define CFQ_SLICE_SCALE (5) 48#define CFQ_HW_QUEUE_MIN (5) 49#define CFQ_SERVICE_SHIFT 12 50 51#define CFQQ_SEEK_THR (sector_t)(8 * 100) 52#define CFQQ_CLOSE_THR (sector_t)(8 * 1024) 53#define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32) 54#define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8) 55 56#define RQ_CIC(rq) \ 57 ((struct cfq_io_context *) (rq)->elevator_private[0]) 58#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private[1]) 59#define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private[2]) 60 61static struct kmem_cache *cfq_pool; 62static struct kmem_cache *cfq_ioc_pool; 63 64static DEFINE_PER_CPU(unsigned long, cfq_ioc_count); 65static struct completion *ioc_gone; 66static DEFINE_SPINLOCK(ioc_gone_lock); 67 68static DEFINE_SPINLOCK(cic_index_lock); 69static DEFINE_IDA(cic_index_ida); 70 71#define CFQ_PRIO_LISTS IOPRIO_BE_NR 72#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) 73#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) 74 75#define sample_valid(samples) ((samples) > 80) 76#define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node) 77 78/* 79 * Most of our rbtree usage is for sorting with min extraction, so 80 * if we cache the leftmost node we don't have to walk down the tree 81 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should 82 * move this into the elevator for the rq sorting as well. 83 */ 84struct cfq_rb_root { 85 struct rb_root rb; 86 struct rb_node *left; 87 unsigned count; 88 unsigned total_weight; 89 u64 min_vdisktime; 90}; 91#define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \ 92 .count = 0, .min_vdisktime = 0, } 93 94/* 95 * Per process-grouping structure 96 */ 97struct cfq_queue { 98 /* reference count */ 99 int ref; 100 /* various state flags, see below */ 101 unsigned int flags; 102 /* parent cfq_data */ 103 struct cfq_data *cfqd; 104 /* service_tree member */ 105 struct rb_node rb_node; 106 /* service_tree key */ 107 unsigned long rb_key; 108 /* prio tree member */ 109 struct rb_node p_node; 110 /* prio tree root we belong to, if any */ 111 struct rb_root *p_root; 112 /* sorted list of pending requests */ 113 struct rb_root sort_list; 114 /* if fifo isn't expired, next request to serve */ 115 struct request *next_rq; 116 /* requests queued in sort_list */ 117 int queued[2]; 118 /* currently allocated requests */ 119 int allocated[2]; 120 /* fifo list of requests in sort_list */ 121 struct list_head fifo; 122 123 /* time when queue got scheduled in to dispatch first request. */ 124 unsigned long dispatch_start; 125 unsigned int allocated_slice; 126 unsigned int slice_dispatch; 127 /* time when first request from queue completed and slice started. */ 128 unsigned long slice_start; 129 unsigned long slice_end; 130 long slice_resid; 131 132 /* pending metadata requests */ 133 int meta_pending; 134 /* number of requests that are on the dispatch list or inside driver */ 135 int dispatched; 136 137 /* io prio of this group */ 138 unsigned short ioprio, org_ioprio; 139 unsigned short ioprio_class, org_ioprio_class; 140 141 pid_t pid; 142 143 u32 seek_history; 144 sector_t last_request_pos; 145 146 struct cfq_rb_root *service_tree; 147 struct cfq_queue *new_cfqq; 148 struct cfq_group *cfqg; 149 /* Number of sectors dispatched from queue in single dispatch round */ 150 unsigned long nr_sectors; 151}; 152 153/* 154 * First index in the service_trees. 155 * IDLE is handled separately, so it has negative index 156 */ 157enum wl_prio_t { 158 BE_WORKLOAD = 0, 159 RT_WORKLOAD = 1, 160 IDLE_WORKLOAD = 2, 161 CFQ_PRIO_NR, 162}; 163 164/* 165 * Second index in the service_trees. 166 */ 167enum wl_type_t { 168 ASYNC_WORKLOAD = 0, 169 SYNC_NOIDLE_WORKLOAD = 1, 170 SYNC_WORKLOAD = 2 171}; 172 173/* This is per cgroup per device grouping structure */ 174struct cfq_group { 175 /* group service_tree member */ 176 struct rb_node rb_node; 177 178 /* group service_tree key */ 179 u64 vdisktime; 180 unsigned int weight; 181 unsigned int new_weight; 182 bool needs_update; 183 184 /* number of cfqq currently on this group */ 185 int nr_cfqq; 186 187 /* 188 * Per group busy queus average. Useful for workload slice calc. We 189 * create the array for each prio class but at run time it is used 190 * only for RT and BE class and slot for IDLE class remains unused. 191 * This is primarily done to avoid confusion and a gcc warning. 192 */ 193 unsigned int busy_queues_avg[CFQ_PRIO_NR]; 194 /* 195 * rr lists of queues with requests. We maintain service trees for 196 * RT and BE classes. These trees are subdivided in subclasses 197 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE 198 * class there is no subclassification and all the cfq queues go on 199 * a single tree service_tree_idle. 200 * Counts are embedded in the cfq_rb_root 201 */ 202 struct cfq_rb_root service_trees[2][3]; 203 struct cfq_rb_root service_tree_idle; 204 205 unsigned long saved_workload_slice; 206 enum wl_type_t saved_workload; 207 enum wl_prio_t saved_serving_prio; 208 struct blkio_group blkg; 209#ifdef CONFIG_CFQ_GROUP_IOSCHED 210 struct hlist_node cfqd_node; 211 int ref; 212#endif 213 /* number of requests that are on the dispatch list or inside driver */ 214 int dispatched; 215}; 216 217/* 218 * Per block device queue structure 219 */ 220struct cfq_data { 221 struct request_queue *queue; 222 /* Root service tree for cfq_groups */ 223 struct cfq_rb_root grp_service_tree; 224 struct cfq_group root_group; 225 226 /* 227 * The priority currently being served 228 */ 229 enum wl_prio_t serving_prio; 230 enum wl_type_t serving_type; 231 unsigned long workload_expires; 232 struct cfq_group *serving_group; 233 234 /* 235 * Each priority tree is sorted by next_request position. These 236 * trees are used when determining if two or more queues are 237 * interleaving requests (see cfq_close_cooperator). 238 */ 239 struct rb_root prio_trees[CFQ_PRIO_LISTS]; 240 241 unsigned int busy_queues; 242 unsigned int busy_sync_queues; 243 244 int rq_in_driver; 245 int rq_in_flight[2]; 246 247 /* 248 * queue-depth detection 249 */ 250 int rq_queued; 251 int hw_tag; 252 /* 253 * hw_tag can be 254 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection) 255 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth) 256 * 0 => no NCQ 257 */ 258 int hw_tag_est_depth; 259 unsigned int hw_tag_samples; 260 261 /* 262 * idle window management 263 */ 264 struct timer_list idle_slice_timer; 265 struct work_struct unplug_work; 266 267 struct cfq_queue *active_queue; 268 struct cfq_io_context *active_cic; 269 270 /* 271 * async queue for each priority case 272 */ 273 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR]; 274 struct cfq_queue *async_idle_cfqq; 275 276 sector_t last_position; 277 278 /* 279 * tunables, see top of file 280 */ 281 unsigned int cfq_quantum; 282 unsigned int cfq_fifo_expire[2]; 283 unsigned int cfq_back_penalty; 284 unsigned int cfq_back_max; 285 unsigned int cfq_slice[2]; 286 unsigned int cfq_slice_async_rq; 287 unsigned int cfq_slice_idle; 288 unsigned int cfq_group_idle; 289 unsigned int cfq_latency; 290 291 unsigned int cic_index; 292 struct list_head cic_list; 293 294 /* 295 * Fallback dummy cfqq for extreme OOM conditions 296 */ 297 struct cfq_queue oom_cfqq; 298 299 unsigned long last_delayed_sync; 300 301 /* List of cfq groups being managed on this device*/ 302 struct hlist_head cfqg_list; 303 304 /* Number of groups which are on blkcg->blkg_list */ 305 unsigned int nr_blkcg_linked_grps; 306}; 307 308static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd); 309 310static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg, 311 enum wl_prio_t prio, 312 enum wl_type_t type) 313{ 314 if (!cfqg) 315 return NULL; 316 317 if (prio == IDLE_WORKLOAD) 318 return &cfqg->service_tree_idle; 319 320 return &cfqg->service_trees[prio][type]; 321} 322 323enum cfqq_state_flags { 324 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ 325 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ 326 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */ 327 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ 328 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ 329 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ 330 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ 331 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ 332 CFQ_CFQQ_FLAG_sync, /* synchronous queue */ 333 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */ 334 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */ 335 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */ 336 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */ 337}; 338 339#define CFQ_CFQQ_FNS(name) \ 340static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ 341{ \ 342 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ 343} \ 344static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ 345{ \ 346 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ 347} \ 348static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ 349{ \ 350 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ 351} 352 353CFQ_CFQQ_FNS(on_rr); 354CFQ_CFQQ_FNS(wait_request); 355CFQ_CFQQ_FNS(must_dispatch); 356CFQ_CFQQ_FNS(must_alloc_slice); 357CFQ_CFQQ_FNS(fifo_expire); 358CFQ_CFQQ_FNS(idle_window); 359CFQ_CFQQ_FNS(prio_changed); 360CFQ_CFQQ_FNS(slice_new); 361CFQ_CFQQ_FNS(sync); 362CFQ_CFQQ_FNS(coop); 363CFQ_CFQQ_FNS(split_coop); 364CFQ_CFQQ_FNS(deep); 365CFQ_CFQQ_FNS(wait_busy); 366#undef CFQ_CFQQ_FNS 367 368#ifdef CONFIG_CFQ_GROUP_IOSCHED 369#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ 370 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \ 371 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \ 372 blkg_path(&(cfqq)->cfqg->blkg), ##args); 373 374#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \ 375 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \ 376 blkg_path(&(cfqg)->blkg), ##args); \ 377 378#else 379#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ 380 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args) 381#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0); 382#endif 383#define cfq_log(cfqd, fmt, args...) \ 384 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args) 385 386/* Traverses through cfq group service trees */ 387#define for_each_cfqg_st(cfqg, i, j, st) \ 388 for (i = 0; i <= IDLE_WORKLOAD; i++) \ 389 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\ 390 : &cfqg->service_tree_idle; \ 391 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \ 392 (i == IDLE_WORKLOAD && j == 0); \ 393 j++, st = i < IDLE_WORKLOAD ? \ 394 &cfqg->service_trees[i][j]: NULL) \ 395 396 397static inline bool iops_mode(struct cfq_data *cfqd) 398{ 399 /* 400 * If we are not idling on queues and it is a NCQ drive, parallel 401 * execution of requests is on and measuring time is not possible 402 * in most of the cases until and unless we drive shallower queue 403 * depths and that becomes a performance bottleneck. In such cases 404 * switch to start providing fairness in terms of number of IOs. 405 */ 406 if (!cfqd->cfq_slice_idle && cfqd->hw_tag) 407 return true; 408 else 409 return false; 410} 411 412static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq) 413{ 414 if (cfq_class_idle(cfqq)) 415 return IDLE_WORKLOAD; 416 if (cfq_class_rt(cfqq)) 417 return RT_WORKLOAD; 418 return BE_WORKLOAD; 419} 420 421 422static enum wl_type_t cfqq_type(struct cfq_queue *cfqq) 423{ 424 if (!cfq_cfqq_sync(cfqq)) 425 return ASYNC_WORKLOAD; 426 if (!cfq_cfqq_idle_window(cfqq)) 427 return SYNC_NOIDLE_WORKLOAD; 428 return SYNC_WORKLOAD; 429} 430 431static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl, 432 struct cfq_data *cfqd, 433 struct cfq_group *cfqg) 434{ 435 if (wl == IDLE_WORKLOAD) 436 return cfqg->service_tree_idle.count; 437 438 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count 439 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count 440 + cfqg->service_trees[wl][SYNC_WORKLOAD].count; 441} 442 443static inline int cfqg_busy_async_queues(struct cfq_data *cfqd, 444 struct cfq_group *cfqg) 445{ 446 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count 447 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count; 448} 449 450static void cfq_dispatch_insert(struct request_queue *, struct request *); 451static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool, 452 struct io_context *, gfp_t); 453static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *, 454 struct io_context *); 455 456static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic, 457 bool is_sync) 458{ 459 return cic->cfqq[is_sync]; 460} 461 462static inline void cic_set_cfqq(struct cfq_io_context *cic, 463 struct cfq_queue *cfqq, bool is_sync) 464{ 465 cic->cfqq[is_sync] = cfqq; 466} 467 468#define CIC_DEAD_KEY 1ul 469#define CIC_DEAD_INDEX_SHIFT 1 470 471static inline void *cfqd_dead_key(struct cfq_data *cfqd) 472{ 473 return (void *)(cfqd->cic_index << CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY); 474} 475 476static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic) 477{ 478 struct cfq_data *cfqd = cic->key; 479 480 if (unlikely((unsigned long) cfqd & CIC_DEAD_KEY)) 481 return NULL; 482 483 return cfqd; 484} 485 486/* 487 * We regard a request as SYNC, if it's either a read or has the SYNC bit 488 * set (in which case it could also be direct WRITE). 489 */ 490static inline bool cfq_bio_sync(struct bio *bio) 491{ 492 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC); 493} 494 495/* 496 * scheduler run of queue, if there are requests pending and no one in the 497 * driver that will restart queueing 498 */ 499static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) 500{ 501 if (cfqd->busy_queues) { 502 cfq_log(cfqd, "schedule dispatch"); 503 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work); 504 } 505} 506 507/* 508 * Scale schedule slice based on io priority. Use the sync time slice only 509 * if a queue is marked sync and has sync io queued. A sync queue with async 510 * io only, should not get full sync slice length. 511 */ 512static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync, 513 unsigned short prio) 514{ 515 const int base_slice = cfqd->cfq_slice[sync]; 516 517 WARN_ON(prio >= IOPRIO_BE_NR); 518 519 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); 520} 521 522static inline int 523cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 524{ 525 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); 526} 527 528static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg) 529{ 530 u64 d = delta << CFQ_SERVICE_SHIFT; 531 532 d = d * BLKIO_WEIGHT_DEFAULT; 533 do_div(d, cfqg->weight); 534 return d; 535} 536 537static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime) 538{ 539 s64 delta = (s64)(vdisktime - min_vdisktime); 540 if (delta > 0) 541 min_vdisktime = vdisktime; 542 543 return min_vdisktime; 544} 545 546static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime) 547{ 548 s64 delta = (s64)(vdisktime - min_vdisktime); 549 if (delta < 0) 550 min_vdisktime = vdisktime; 551 552 return min_vdisktime; 553} 554 555static void update_min_vdisktime(struct cfq_rb_root *st) 556{ 557 struct cfq_group *cfqg; 558 559 if (st->left) { 560 cfqg = rb_entry_cfqg(st->left); 561 st->min_vdisktime = max_vdisktime(st->min_vdisktime, 562 cfqg->vdisktime); 563 } 564} 565 566/* 567 * get averaged number of queues of RT/BE priority. 568 * average is updated, with a formula that gives more weight to higher numbers, 569 * to quickly follows sudden increases and decrease slowly 570 */ 571 572static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd, 573 struct cfq_group *cfqg, bool rt) 574{ 575 unsigned min_q, max_q; 576 unsigned mult = cfq_hist_divisor - 1; 577 unsigned round = cfq_hist_divisor / 2; 578 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg); 579 580 min_q = min(cfqg->busy_queues_avg[rt], busy); 581 max_q = max(cfqg->busy_queues_avg[rt], busy); 582 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) / 583 cfq_hist_divisor; 584 return cfqg->busy_queues_avg[rt]; 585} 586 587static inline unsigned 588cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg) 589{ 590 struct cfq_rb_root *st = &cfqd->grp_service_tree; 591 592 return cfq_target_latency * cfqg->weight / st->total_weight; 593} 594 595static inline unsigned 596cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 597{ 598 unsigned slice = cfq_prio_to_slice(cfqd, cfqq); 599 if (cfqd->cfq_latency) { 600 /* 601 * interested queues (we consider only the ones with the same 602 * priority class in the cfq group) 603 */ 604 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg, 605 cfq_class_rt(cfqq)); 606 unsigned sync_slice = cfqd->cfq_slice[1]; 607 unsigned expect_latency = sync_slice * iq; 608 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg); 609 610 if (expect_latency > group_slice) { 611 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle; 612 /* scale low_slice according to IO priority 613 * and sync vs async */ 614 unsigned low_slice = 615 min(slice, base_low_slice * slice / sync_slice); 616 /* the adapted slice value is scaled to fit all iqs 617 * into the target latency */ 618 slice = max(slice * group_slice / expect_latency, 619 low_slice); 620 } 621 } 622 return slice; 623} 624 625static inline void 626cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 627{ 628 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq); 629 630 cfqq->slice_start = jiffies; 631 cfqq->slice_end = jiffies + slice; 632 cfqq->allocated_slice = slice; 633 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies); 634} 635 636/* 637 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end 638 * isn't valid until the first request from the dispatch is activated 639 * and the slice time set. 640 */ 641static inline bool cfq_slice_used(struct cfq_queue *cfqq) 642{ 643 if (cfq_cfqq_slice_new(cfqq)) 644 return false; 645 if (time_before(jiffies, cfqq->slice_end)) 646 return false; 647 648 return true; 649} 650 651/* 652 * Lifted from AS - choose which of rq1 and rq2 that is best served now. 653 * We choose the request that is closest to the head right now. Distance 654 * behind the head is penalized and only allowed to a certain extent. 655 */ 656static struct request * 657cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last) 658{ 659 sector_t s1, s2, d1 = 0, d2 = 0; 660 unsigned long back_max; 661#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ 662#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ 663 unsigned wrap = 0; /* bit mask: requests behind the disk head? */ 664 665 if (rq1 == NULL || rq1 == rq2) 666 return rq2; 667 if (rq2 == NULL) 668 return rq1; 669 670 if (rq_is_sync(rq1) && !rq_is_sync(rq2)) 671 return rq1; 672 else if (rq_is_sync(rq2) && !rq_is_sync(rq1)) 673 return rq2; 674 if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META)) 675 return rq1; 676 else if ((rq2->cmd_flags & REQ_META) && 677 !(rq1->cmd_flags & REQ_META)) 678 return rq2; 679 680 s1 = blk_rq_pos(rq1); 681 s2 = blk_rq_pos(rq2); 682 683 /* 684 * by definition, 1KiB is 2 sectors 685 */ 686 back_max = cfqd->cfq_back_max * 2; 687 688 /* 689 * Strict one way elevator _except_ in the case where we allow 690 * short backward seeks which are biased as twice the cost of a 691 * similar forward seek. 692 */ 693 if (s1 >= last) 694 d1 = s1 - last; 695 else if (s1 + back_max >= last) 696 d1 = (last - s1) * cfqd->cfq_back_penalty; 697 else 698 wrap |= CFQ_RQ1_WRAP; 699 700 if (s2 >= last) 701 d2 = s2 - last; 702 else if (s2 + back_max >= last) 703 d2 = (last - s2) * cfqd->cfq_back_penalty; 704 else 705 wrap |= CFQ_RQ2_WRAP; 706 707 /* Found required data */ 708 709 /* 710 * By doing switch() on the bit mask "wrap" we avoid having to 711 * check two variables for all permutations: --> faster! 712 */ 713 switch (wrap) { 714 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ 715 if (d1 < d2) 716 return rq1; 717 else if (d2 < d1) 718 return rq2; 719 else { 720 if (s1 >= s2) 721 return rq1; 722 else 723 return rq2; 724 } 725 726 case CFQ_RQ2_WRAP: 727 return rq1; 728 case CFQ_RQ1_WRAP: 729 return rq2; 730 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ 731 default: 732 /* 733 * Since both rqs are wrapped, 734 * start with the one that's further behind head 735 * (--> only *one* back seek required), 736 * since back seek takes more time than forward. 737 */ 738 if (s1 <= s2) 739 return rq1; 740 else 741 return rq2; 742 } 743} 744 745/* 746 * The below is leftmost cache rbtree addon 747 */ 748static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root) 749{ 750 /* Service tree is empty */ 751 if (!root->count) 752 return NULL; 753 754 if (!root->left) 755 root->left = rb_first(&root->rb); 756 757 if (root->left) 758 return rb_entry(root->left, struct cfq_queue, rb_node); 759 760 return NULL; 761} 762 763static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root) 764{ 765 if (!root->left) 766 root->left = rb_first(&root->rb); 767 768 if (root->left) 769 return rb_entry_cfqg(root->left); 770 771 return NULL; 772} 773 774static void rb_erase_init(struct rb_node *n, struct rb_root *root) 775{ 776 rb_erase(n, root); 777 RB_CLEAR_NODE(n); 778} 779 780static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) 781{ 782 if (root->left == n) 783 root->left = NULL; 784 rb_erase_init(n, &root->rb); 785 --root->count; 786} 787 788/* 789 * would be nice to take fifo expire time into account as well 790 */ 791static struct request * 792cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, 793 struct request *last) 794{ 795 struct rb_node *rbnext = rb_next(&last->rb_node); 796 struct rb_node *rbprev = rb_prev(&last->rb_node); 797 struct request *next = NULL, *prev = NULL; 798 799 BUG_ON(RB_EMPTY_NODE(&last->rb_node)); 800 801 if (rbprev) 802 prev = rb_entry_rq(rbprev); 803 804 if (rbnext) 805 next = rb_entry_rq(rbnext); 806 else { 807 rbnext = rb_first(&cfqq->sort_list); 808 if (rbnext && rbnext != &last->rb_node) 809 next = rb_entry_rq(rbnext); 810 } 811 812 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last)); 813} 814 815static unsigned long cfq_slice_offset(struct cfq_data *cfqd, 816 struct cfq_queue *cfqq) 817{ 818 /* 819 * just an approximation, should be ok. 820 */ 821 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) - 822 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); 823} 824 825static inline s64 826cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg) 827{ 828 return cfqg->vdisktime - st->min_vdisktime; 829} 830 831static void 832__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) 833{ 834 struct rb_node **node = &st->rb.rb_node; 835 struct rb_node *parent = NULL; 836 struct cfq_group *__cfqg; 837 s64 key = cfqg_key(st, cfqg); 838 int left = 1; 839 840 while (*node != NULL) { 841 parent = *node; 842 __cfqg = rb_entry_cfqg(parent); 843 844 if (key < cfqg_key(st, __cfqg)) 845 node = &parent->rb_left; 846 else { 847 node = &parent->rb_right; 848 left = 0; 849 } 850 } 851 852 if (left) 853 st->left = &cfqg->rb_node; 854 855 rb_link_node(&cfqg->rb_node, parent, node); 856 rb_insert_color(&cfqg->rb_node, &st->rb); 857} 858 859static void 860cfq_update_group_weight(struct cfq_group *cfqg) 861{ 862 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); 863 if (cfqg->needs_update) { 864 cfqg->weight = cfqg->new_weight; 865 cfqg->needs_update = false; 866 } 867} 868 869static void 870cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) 871{ 872 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); 873 874 cfq_update_group_weight(cfqg); 875 __cfq_group_service_tree_add(st, cfqg); 876 st->total_weight += cfqg->weight; 877} 878 879static void 880cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg) 881{ 882 struct cfq_rb_root *st = &cfqd->grp_service_tree; 883 struct cfq_group *__cfqg; 884 struct rb_node *n; 885 886 cfqg->nr_cfqq++; 887 if (!RB_EMPTY_NODE(&cfqg->rb_node)) 888 return; 889 890 /* 891 * Currently put the group at the end. Later implement something 892 * so that groups get lesser vtime based on their weights, so that 893 * if group does not loose all if it was not continuously backlogged. 894 */ 895 n = rb_last(&st->rb); 896 if (n) { 897 __cfqg = rb_entry_cfqg(n); 898 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY; 899 } else 900 cfqg->vdisktime = st->min_vdisktime; 901 cfq_group_service_tree_add(st, cfqg); 902} 903 904static void 905cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg) 906{ 907 st->total_weight -= cfqg->weight; 908 if (!RB_EMPTY_NODE(&cfqg->rb_node)) 909 cfq_rb_erase(&cfqg->rb_node, st); 910} 911 912static void 913cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg) 914{ 915 struct cfq_rb_root *st = &cfqd->grp_service_tree; 916 917 BUG_ON(cfqg->nr_cfqq < 1); 918 cfqg->nr_cfqq--; 919 920 /* If there are other cfq queues under this group, don't delete it */ 921 if (cfqg->nr_cfqq) 922 return; 923 924 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group"); 925 cfq_group_service_tree_del(st, cfqg); 926 cfqg->saved_workload_slice = 0; 927 cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1); 928} 929 930static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq, 931 unsigned int *unaccounted_time) 932{ 933 unsigned int slice_used; 934 935 /* 936 * Queue got expired before even a single request completed or 937 * got expired immediately after first request completion. 938 */ 939 if (!cfqq->slice_start || cfqq->slice_start == jiffies) { 940 /* 941 * Also charge the seek time incurred to the group, otherwise 942 * if there are mutiple queues in the group, each can dispatch 943 * a single request on seeky media and cause lots of seek time 944 * and group will never know it. 945 */ 946 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start), 947 1); 948 } else { 949 slice_used = jiffies - cfqq->slice_start; 950 if (slice_used > cfqq->allocated_slice) { 951 *unaccounted_time = slice_used - cfqq->allocated_slice; 952 slice_used = cfqq->allocated_slice; 953 } 954 if (time_after(cfqq->slice_start, cfqq->dispatch_start)) 955 *unaccounted_time += cfqq->slice_start - 956 cfqq->dispatch_start; 957 } 958 959 return slice_used; 960} 961 962static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg, 963 struct cfq_queue *cfqq) 964{ 965 struct cfq_rb_root *st = &cfqd->grp_service_tree; 966 unsigned int used_sl, charge, unaccounted_sl = 0; 967 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg) 968 - cfqg->service_tree_idle.count; 969 970 BUG_ON(nr_sync < 0); 971 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl); 972 973 if (iops_mode(cfqd)) 974 charge = cfqq->slice_dispatch; 975 else if (!cfq_cfqq_sync(cfqq) && !nr_sync) 976 charge = cfqq->allocated_slice; 977 978 /* Can't update vdisktime while group is on service tree */ 979 cfq_group_service_tree_del(st, cfqg); 980 cfqg->vdisktime += cfq_scale_slice(charge, cfqg); 981 /* If a new weight was requested, update now, off tree */ 982 cfq_group_service_tree_add(st, cfqg); 983 984 /* This group is being expired. Save the context */ 985 if (time_after(cfqd->workload_expires, jiffies)) { 986 cfqg->saved_workload_slice = cfqd->workload_expires 987 - jiffies; 988 cfqg->saved_workload = cfqd->serving_type; 989 cfqg->saved_serving_prio = cfqd->serving_prio; 990 } else 991 cfqg->saved_workload_slice = 0; 992 993 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime, 994 st->min_vdisktime); 995 cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u disp=%u charge=%u iops=%u" 996 " sect=%u", used_sl, cfqq->slice_dispatch, charge, 997 iops_mode(cfqd), cfqq->nr_sectors); 998 cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl, 999 unaccounted_sl); 1000 cfq_blkiocg_set_start_empty_time(&cfqg->blkg); 1001} 1002 1003#ifdef CONFIG_CFQ_GROUP_IOSCHED 1004static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg) 1005{ 1006 if (blkg) 1007 return container_of(blkg, struct cfq_group, blkg); 1008 return NULL; 1009} 1010 1011void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg, 1012 unsigned int weight) 1013{ 1014 struct cfq_group *cfqg = cfqg_of_blkg(blkg); 1015 cfqg->new_weight = weight; 1016 cfqg->needs_update = true; 1017} 1018 1019static void cfq_init_add_cfqg_lists(struct cfq_data *cfqd, 1020 struct cfq_group *cfqg, struct blkio_cgroup *blkcg) 1021{ 1022 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info; 1023 unsigned int major, minor; 1024 1025 /* 1026 * Add group onto cgroup list. It might happen that bdi->dev is 1027 * not initialized yet. Initialize this new group without major 1028 * and minor info and this info will be filled in once a new thread 1029 * comes for IO. 1030 */ 1031 if (bdi->dev) { 1032 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); 1033 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, 1034 (void *)cfqd, MKDEV(major, minor)); 1035 } else 1036 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, 1037 (void *)cfqd, 0); 1038 1039 cfqd->nr_blkcg_linked_grps++; 1040 cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev); 1041 1042 /* Add group on cfqd list */ 1043 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list); 1044} 1045 1046/* 1047 * Should be called from sleepable context. No request queue lock as per 1048 * cpu stats are allocated dynamically and alloc_percpu needs to be called 1049 * from sleepable context. 1050 */ 1051static struct cfq_group * cfq_alloc_cfqg(struct cfq_data *cfqd) 1052{ 1053 struct cfq_group *cfqg = NULL; 1054 int i, j, ret; 1055 struct cfq_rb_root *st; 1056 1057 cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node); 1058 if (!cfqg) 1059 return NULL; 1060 1061 for_each_cfqg_st(cfqg, i, j, st) 1062 *st = CFQ_RB_ROOT; 1063 RB_CLEAR_NODE(&cfqg->rb_node); 1064 1065 /* 1066 * Take the initial reference that will be released on destroy 1067 * This can be thought of a joint reference by cgroup and 1068 * elevator which will be dropped by either elevator exit 1069 * or cgroup deletion path depending on who is exiting first. 1070 */ 1071 cfqg->ref = 1; 1072 1073 ret = blkio_alloc_blkg_stats(&cfqg->blkg); 1074 if (ret) { 1075 kfree(cfqg); 1076 return NULL; 1077 } 1078 1079 return cfqg; 1080} 1081 1082static struct cfq_group * 1083cfq_find_cfqg(struct cfq_data *cfqd, struct blkio_cgroup *blkcg) 1084{ 1085 struct cfq_group *cfqg = NULL; 1086 void *key = cfqd; 1087 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info; 1088 unsigned int major, minor; 1089 1090 /* 1091 * This is the common case when there are no blkio cgroups. 1092 * Avoid lookup in this case 1093 */ 1094 if (blkcg == &blkio_root_cgroup) 1095 cfqg = &cfqd->root_group; 1096 else 1097 cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key)); 1098 1099 if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) { 1100 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); 1101 cfqg->blkg.dev = MKDEV(major, minor); 1102 } 1103 1104 return cfqg; 1105} 1106 1107/* 1108 * Search for the cfq group current task belongs to. request_queue lock must 1109 * be held. 1110 */ 1111static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd) 1112{ 1113 struct blkio_cgroup *blkcg; 1114 struct cfq_group *cfqg = NULL, *__cfqg = NULL; 1115 struct request_queue *q = cfqd->queue; 1116 1117 rcu_read_lock(); 1118 blkcg = task_blkio_cgroup(current); 1119 cfqg = cfq_find_cfqg(cfqd, blkcg); 1120 if (cfqg) { 1121 rcu_read_unlock(); 1122 return cfqg; 1123 } 1124 1125 /* 1126 * Need to allocate a group. Allocation of group also needs allocation 1127 * of per cpu stats which in-turn takes a mutex() and can block. Hence 1128 * we need to drop rcu lock and queue_lock before we call alloc. 1129 * 1130 * Not taking any queue reference here and assuming that queue is 1131 * around by the time we return. CFQ queue allocation code does 1132 * the same. It might be racy though. 1133 */ 1134 1135 rcu_read_unlock(); 1136 spin_unlock_irq(q->queue_lock); 1137 1138 cfqg = cfq_alloc_cfqg(cfqd); 1139 1140 spin_lock_irq(q->queue_lock); 1141 1142 rcu_read_lock(); 1143 blkcg = task_blkio_cgroup(current); 1144 1145 /* 1146 * If some other thread already allocated the group while we were 1147 * not holding queue lock, free up the group 1148 */ 1149 __cfqg = cfq_find_cfqg(cfqd, blkcg); 1150 1151 if (__cfqg) { 1152 kfree(cfqg); 1153 rcu_read_unlock(); 1154 return __cfqg; 1155 } 1156 1157 if (!cfqg) 1158 cfqg = &cfqd->root_group; 1159 1160 cfq_init_add_cfqg_lists(cfqd, cfqg, blkcg); 1161 rcu_read_unlock(); 1162 return cfqg; 1163} 1164 1165static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) 1166{ 1167 cfqg->ref++; 1168 return cfqg; 1169} 1170 1171static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) 1172{ 1173 /* Currently, all async queues are mapped to root group */ 1174 if (!cfq_cfqq_sync(cfqq)) 1175 cfqg = &cfqq->cfqd->root_group; 1176 1177 cfqq->cfqg = cfqg; 1178 /* cfqq reference on cfqg */ 1179 cfqq->cfqg->ref++; 1180} 1181 1182static void cfq_put_cfqg(struct cfq_group *cfqg) 1183{ 1184 struct cfq_rb_root *st; 1185 int i, j; 1186 1187 BUG_ON(cfqg->ref <= 0); 1188 cfqg->ref--; 1189 if (cfqg->ref) 1190 return; 1191 for_each_cfqg_st(cfqg, i, j, st) 1192 BUG_ON(!RB_EMPTY_ROOT(&st->rb)); 1193 free_percpu(cfqg->blkg.stats_cpu); 1194 kfree(cfqg); 1195} 1196 1197static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg) 1198{ 1199 /* Something wrong if we are trying to remove same group twice */ 1200 BUG_ON(hlist_unhashed(&cfqg->cfqd_node)); 1201 1202 hlist_del_init(&cfqg->cfqd_node); 1203 1204 /* 1205 * Put the reference taken at the time of creation so that when all 1206 * queues are gone, group can be destroyed. 1207 */ 1208 cfq_put_cfqg(cfqg); 1209} 1210 1211static void cfq_release_cfq_groups(struct cfq_data *cfqd) 1212{ 1213 struct hlist_node *pos, *n; 1214 struct cfq_group *cfqg; 1215 1216 hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) { 1217 /* 1218 * If cgroup removal path got to blk_group first and removed 1219 * it from cgroup list, then it will take care of destroying 1220 * cfqg also. 1221 */ 1222 if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg)) 1223 cfq_destroy_cfqg(cfqd, cfqg); 1224 } 1225} 1226 1227/* 1228 * Blk cgroup controller notification saying that blkio_group object is being 1229 * delinked as associated cgroup object is going away. That also means that 1230 * no new IO will come in this group. So get rid of this group as soon as 1231 * any pending IO in the group is finished. 1232 * 1233 * This function is called under rcu_read_lock(). key is the rcu protected 1234 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu 1235 * read lock. 1236 * 1237 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means 1238 * it should not be NULL as even if elevator was exiting, cgroup deltion 1239 * path got to it first. 1240 */ 1241void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg) 1242{ 1243 unsigned long flags; 1244 struct cfq_data *cfqd = key; 1245 1246 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 1247 cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg)); 1248 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 1249} 1250 1251#else /* GROUP_IOSCHED */ 1252static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd) 1253{ 1254 return &cfqd->root_group; 1255} 1256 1257static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) 1258{ 1259 return cfqg; 1260} 1261 1262static inline void 1263cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) { 1264 cfqq->cfqg = cfqg; 1265} 1266 1267static void cfq_release_cfq_groups(struct cfq_data *cfqd) {} 1268static inline void cfq_put_cfqg(struct cfq_group *cfqg) {} 1269 1270#endif /* GROUP_IOSCHED */ 1271 1272/* 1273 * The cfqd->service_trees holds all pending cfq_queue's that have 1274 * requests waiting to be processed. It is sorted in the order that 1275 * we will service the queues. 1276 */ 1277static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1278 bool add_front) 1279{ 1280 struct rb_node **p, *parent; 1281 struct cfq_queue *__cfqq; 1282 unsigned long rb_key; 1283 struct cfq_rb_root *service_tree; 1284 int left; 1285 int new_cfqq = 1; 1286 int group_changed = 0; 1287 1288 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq), 1289 cfqq_type(cfqq)); 1290 if (cfq_class_idle(cfqq)) { 1291 rb_key = CFQ_IDLE_DELAY; 1292 parent = rb_last(&service_tree->rb); 1293 if (parent && parent != &cfqq->rb_node) { 1294 __cfqq = rb_entry(parent, struct cfq_queue, rb_node); 1295 rb_key += __cfqq->rb_key; 1296 } else 1297 rb_key += jiffies; 1298 } else if (!add_front) { 1299 /* 1300 * Get our rb key offset. Subtract any residual slice 1301 * value carried from last service. A negative resid 1302 * count indicates slice overrun, and this should position 1303 * the next service time further away in the tree. 1304 */ 1305 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; 1306 rb_key -= cfqq->slice_resid; 1307 cfqq->slice_resid = 0; 1308 } else { 1309 rb_key = -HZ; 1310 __cfqq = cfq_rb_first(service_tree); 1311 rb_key += __cfqq ? __cfqq->rb_key : jiffies; 1312 } 1313 1314 if (!RB_EMPTY_NODE(&cfqq->rb_node)) { 1315 new_cfqq = 0; 1316 /* 1317 * same position, nothing more to do 1318 */ 1319 if (rb_key == cfqq->rb_key && 1320 cfqq->service_tree == service_tree) 1321 return; 1322 1323 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); 1324 cfqq->service_tree = NULL; 1325 } 1326 1327 left = 1; 1328 parent = NULL; 1329 cfqq->service_tree = service_tree; 1330 p = &service_tree->rb.rb_node; 1331 while (*p) { 1332 struct rb_node **n; 1333 1334 parent = *p; 1335 __cfqq = rb_entry(parent, struct cfq_queue, rb_node); 1336 1337 /* 1338 * sort by key, that represents service time. 1339 */ 1340 if (time_before(rb_key, __cfqq->rb_key)) 1341 n = &(*p)->rb_left; 1342 else { 1343 n = &(*p)->rb_right; 1344 left = 0; 1345 } 1346 1347 p = n; 1348 } 1349 1350 if (left) 1351 service_tree->left = &cfqq->rb_node; 1352 1353 cfqq->rb_key = rb_key; 1354 rb_link_node(&cfqq->rb_node, parent, p); 1355 rb_insert_color(&cfqq->rb_node, &service_tree->rb); 1356 service_tree->count++; 1357 if ((add_front || !new_cfqq) && !group_changed) 1358 return; 1359 cfq_group_notify_queue_add(cfqd, cfqq->cfqg); 1360} 1361 1362static struct cfq_queue * 1363cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root, 1364 sector_t sector, struct rb_node **ret_parent, 1365 struct rb_node ***rb_link) 1366{ 1367 struct rb_node **p, *parent; 1368 struct cfq_queue *cfqq = NULL; 1369 1370 parent = NULL; 1371 p = &root->rb_node; 1372 while (*p) { 1373 struct rb_node **n; 1374 1375 parent = *p; 1376 cfqq = rb_entry(parent, struct cfq_queue, p_node); 1377 1378 /* 1379 * Sort strictly based on sector. Smallest to the left, 1380 * largest to the right. 1381 */ 1382 if (sector > blk_rq_pos(cfqq->next_rq)) 1383 n = &(*p)->rb_right; 1384 else if (sector < blk_rq_pos(cfqq->next_rq)) 1385 n = &(*p)->rb_left; 1386 else 1387 break; 1388 p = n; 1389 cfqq = NULL; 1390 } 1391 1392 *ret_parent = parent; 1393 if (rb_link) 1394 *rb_link = p; 1395 return cfqq; 1396} 1397 1398static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1399{ 1400 struct rb_node **p, *parent; 1401 struct cfq_queue *__cfqq; 1402 1403 if (cfqq->p_root) { 1404 rb_erase(&cfqq->p_node, cfqq->p_root); 1405 cfqq->p_root = NULL; 1406 } 1407 1408 if (cfq_class_idle(cfqq)) 1409 return; 1410 if (!cfqq->next_rq) 1411 return; 1412 1413 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio]; 1414 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, 1415 blk_rq_pos(cfqq->next_rq), &parent, &p); 1416 if (!__cfqq) { 1417 rb_link_node(&cfqq->p_node, parent, p); 1418 rb_insert_color(&cfqq->p_node, cfqq->p_root); 1419 } else 1420 cfqq->p_root = NULL; 1421} 1422 1423/* 1424 * Update cfqq's position in the service tree. 1425 */ 1426static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1427{ 1428 /* 1429 * Resorting requires the cfqq to be on the RR list already. 1430 */ 1431 if (cfq_cfqq_on_rr(cfqq)) { 1432 cfq_service_tree_add(cfqd, cfqq, 0); 1433 cfq_prio_tree_add(cfqd, cfqq); 1434 } 1435} 1436 1437/* 1438 * add to busy list of queues for service, trying to be fair in ordering 1439 * the pending list according to last request service 1440 */ 1441static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1442{ 1443 cfq_log_cfqq(cfqd, cfqq, "add_to_rr"); 1444 BUG_ON(cfq_cfqq_on_rr(cfqq)); 1445 cfq_mark_cfqq_on_rr(cfqq); 1446 cfqd->busy_queues++; 1447 if (cfq_cfqq_sync(cfqq)) 1448 cfqd->busy_sync_queues++; 1449 1450 cfq_resort_rr_list(cfqd, cfqq); 1451} 1452 1453/* 1454 * Called when the cfqq no longer has requests pending, remove it from 1455 * the service tree. 1456 */ 1457static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1458{ 1459 cfq_log_cfqq(cfqd, cfqq, "del_from_rr"); 1460 BUG_ON(!cfq_cfqq_on_rr(cfqq)); 1461 cfq_clear_cfqq_on_rr(cfqq); 1462 1463 if (!RB_EMPTY_NODE(&cfqq->rb_node)) { 1464 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); 1465 cfqq->service_tree = NULL; 1466 } 1467 if (cfqq->p_root) { 1468 rb_erase(&cfqq->p_node, cfqq->p_root); 1469 cfqq->p_root = NULL; 1470 } 1471 1472 cfq_group_notify_queue_del(cfqd, cfqq->cfqg); 1473 BUG_ON(!cfqd->busy_queues); 1474 cfqd->busy_queues--; 1475 if (cfq_cfqq_sync(cfqq)) 1476 cfqd->busy_sync_queues--; 1477} 1478 1479/* 1480 * rb tree support functions 1481 */ 1482static void cfq_del_rq_rb(struct request *rq) 1483{ 1484 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1485 const int sync = rq_is_sync(rq); 1486 1487 BUG_ON(!cfqq->queued[sync]); 1488 cfqq->queued[sync]--; 1489 1490 elv_rb_del(&cfqq->sort_list, rq); 1491 1492 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) { 1493 /* 1494 * Queue will be deleted from service tree when we actually 1495 * expire it later. Right now just remove it from prio tree 1496 * as it is empty. 1497 */ 1498 if (cfqq->p_root) { 1499 rb_erase(&cfqq->p_node, cfqq->p_root); 1500 cfqq->p_root = NULL; 1501 } 1502 } 1503} 1504 1505static void cfq_add_rq_rb(struct request *rq) 1506{ 1507 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1508 struct cfq_data *cfqd = cfqq->cfqd; 1509 struct request *__alias, *prev; 1510 1511 cfqq->queued[rq_is_sync(rq)]++; 1512 1513 /* 1514 * looks a little odd, but the first insert might return an alias. 1515 * if that happens, put the alias on the dispatch list 1516 */ 1517 while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL) 1518 cfq_dispatch_insert(cfqd->queue, __alias); 1519 1520 if (!cfq_cfqq_on_rr(cfqq)) 1521 cfq_add_cfqq_rr(cfqd, cfqq); 1522 1523 /* 1524 * check if this request is a better next-serve candidate 1525 */ 1526 prev = cfqq->next_rq; 1527 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position); 1528 1529 /* 1530 * adjust priority tree position, if ->next_rq changes 1531 */ 1532 if (prev != cfqq->next_rq) 1533 cfq_prio_tree_add(cfqd, cfqq); 1534 1535 BUG_ON(!cfqq->next_rq); 1536} 1537 1538static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) 1539{ 1540 elv_rb_del(&cfqq->sort_list, rq); 1541 cfqq->queued[rq_is_sync(rq)]--; 1542 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg, 1543 rq_data_dir(rq), rq_is_sync(rq)); 1544 cfq_add_rq_rb(rq); 1545 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg, 1546 &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq), 1547 rq_is_sync(rq)); 1548} 1549 1550static struct request * 1551cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) 1552{ 1553 struct task_struct *tsk = current; 1554 struct cfq_io_context *cic; 1555 struct cfq_queue *cfqq; 1556 1557 cic = cfq_cic_lookup(cfqd, tsk->io_context); 1558 if (!cic) 1559 return NULL; 1560 1561 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); 1562 if (cfqq) { 1563 sector_t sector = bio->bi_sector + bio_sectors(bio); 1564 1565 return elv_rb_find(&cfqq->sort_list, sector); 1566 } 1567 1568 return NULL; 1569} 1570 1571static void cfq_activate_request(struct request_queue *q, struct request *rq) 1572{ 1573 struct cfq_data *cfqd = q->elevator->elevator_data; 1574 1575 cfqd->rq_in_driver++; 1576 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d", 1577 cfqd->rq_in_driver); 1578 1579 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); 1580} 1581 1582static void cfq_deactivate_request(struct request_queue *q, struct request *rq) 1583{ 1584 struct cfq_data *cfqd = q->elevator->elevator_data; 1585 1586 WARN_ON(!cfqd->rq_in_driver); 1587 cfqd->rq_in_driver--; 1588 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d", 1589 cfqd->rq_in_driver); 1590} 1591 1592static void cfq_remove_request(struct request *rq) 1593{ 1594 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1595 1596 if (cfqq->next_rq == rq) 1597 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); 1598 1599 list_del_init(&rq->queuelist); 1600 cfq_del_rq_rb(rq); 1601 1602 cfqq->cfqd->rq_queued--; 1603 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg, 1604 rq_data_dir(rq), rq_is_sync(rq)); 1605 if (rq->cmd_flags & REQ_META) { 1606 WARN_ON(!cfqq->meta_pending); 1607 cfqq->meta_pending--; 1608 } 1609} 1610 1611static int cfq_merge(struct request_queue *q, struct request **req, 1612 struct bio *bio) 1613{ 1614 struct cfq_data *cfqd = q->elevator->elevator_data; 1615 struct request *__rq; 1616 1617 __rq = cfq_find_rq_fmerge(cfqd, bio); 1618 if (__rq && elv_rq_merge_ok(__rq, bio)) { 1619 *req = __rq; 1620 return ELEVATOR_FRONT_MERGE; 1621 } 1622 1623 return ELEVATOR_NO_MERGE; 1624} 1625 1626static void cfq_merged_request(struct request_queue *q, struct request *req, 1627 int type) 1628{ 1629 if (type == ELEVATOR_FRONT_MERGE) { 1630 struct cfq_queue *cfqq = RQ_CFQQ(req); 1631 1632 cfq_reposition_rq_rb(cfqq, req); 1633 } 1634} 1635 1636static void cfq_bio_merged(struct request_queue *q, struct request *req, 1637 struct bio *bio) 1638{ 1639 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg, 1640 bio_data_dir(bio), cfq_bio_sync(bio)); 1641} 1642 1643static void 1644cfq_merged_requests(struct request_queue *q, struct request *rq, 1645 struct request *next) 1646{ 1647 struct cfq_queue *cfqq = RQ_CFQQ(rq); 1648 /* 1649 * reposition in fifo if next is older than rq 1650 */ 1651 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && 1652 time_before(rq_fifo_time(next), rq_fifo_time(rq))) { 1653 list_move(&rq->queuelist, &next->queuelist); 1654 rq_set_fifo_time(rq, rq_fifo_time(next)); 1655 } 1656 1657 if (cfqq->next_rq == next) 1658 cfqq->next_rq = rq; 1659 cfq_remove_request(next); 1660 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg, 1661 rq_data_dir(next), rq_is_sync(next)); 1662} 1663 1664static int cfq_allow_merge(struct request_queue *q, struct request *rq, 1665 struct bio *bio) 1666{ 1667 struct cfq_data *cfqd = q->elevator->elevator_data; 1668 struct cfq_io_context *cic; 1669 struct cfq_queue *cfqq; 1670 1671 /* 1672 * Disallow merge of a sync bio into an async request. 1673 */ 1674 if (cfq_bio_sync(bio) && !rq_is_sync(rq)) 1675 return false; 1676 1677 /* 1678 * Lookup the cfqq that this bio will be queued with. Allow 1679 * merge only if rq is queued there. 1680 */ 1681 cic = cfq_cic_lookup(cfqd, current->io_context); 1682 if (!cic) 1683 return false; 1684 1685 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); 1686 return cfqq == RQ_CFQQ(rq); 1687} 1688 1689static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1690{ 1691 del_timer(&cfqd->idle_slice_timer); 1692 cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg); 1693} 1694 1695static void __cfq_set_active_queue(struct cfq_data *cfqd, 1696 struct cfq_queue *cfqq) 1697{ 1698 if (cfqq) { 1699 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d", 1700 cfqd->serving_prio, cfqd->serving_type); 1701 cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg); 1702 cfqq->slice_start = 0; 1703 cfqq->dispatch_start = jiffies; 1704 cfqq->allocated_slice = 0; 1705 cfqq->slice_end = 0; 1706 cfqq->slice_dispatch = 0; 1707 cfqq->nr_sectors = 0; 1708 1709 cfq_clear_cfqq_wait_request(cfqq); 1710 cfq_clear_cfqq_must_dispatch(cfqq); 1711 cfq_clear_cfqq_must_alloc_slice(cfqq); 1712 cfq_clear_cfqq_fifo_expire(cfqq); 1713 cfq_mark_cfqq_slice_new(cfqq); 1714 1715 cfq_del_timer(cfqd, cfqq); 1716 } 1717 1718 cfqd->active_queue = cfqq; 1719} 1720 1721/* 1722 * current cfqq expired its slice (or was too idle), select new one 1723 */ 1724static void 1725__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1726 bool timed_out) 1727{ 1728 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out); 1729 1730 if (cfq_cfqq_wait_request(cfqq)) 1731 cfq_del_timer(cfqd, cfqq); 1732 1733 cfq_clear_cfqq_wait_request(cfqq); 1734 cfq_clear_cfqq_wait_busy(cfqq); 1735 1736 /* 1737 * If this cfqq is shared between multiple processes, check to 1738 * make sure that those processes are still issuing I/Os within 1739 * the mean seek distance. If not, it may be time to break the 1740 * queues apart again. 1741 */ 1742 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq)) 1743 cfq_mark_cfqq_split_coop(cfqq); 1744 1745 /* 1746 * store what was left of this slice, if the queue idled/timed out 1747 */ 1748 if (timed_out) { 1749 if (cfq_cfqq_slice_new(cfqq)) 1750 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq); 1751 else 1752 cfqq->slice_resid = cfqq->slice_end - jiffies; 1753 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid); 1754 } 1755 1756 cfq_group_served(cfqd, cfqq->cfqg, cfqq); 1757 1758 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) 1759 cfq_del_cfqq_rr(cfqd, cfqq); 1760 1761 cfq_resort_rr_list(cfqd, cfqq); 1762 1763 if (cfqq == cfqd->active_queue) 1764 cfqd->active_queue = NULL; 1765 1766 if (cfqd->active_cic) { 1767 put_io_context(cfqd->active_cic->ioc); 1768 cfqd->active_cic = NULL; 1769 } 1770} 1771 1772static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out) 1773{ 1774 struct cfq_queue *cfqq = cfqd->active_queue; 1775 1776 if (cfqq) 1777 __cfq_slice_expired(cfqd, cfqq, timed_out); 1778} 1779 1780/* 1781 * Get next queue for service. Unless we have a queue preemption, 1782 * we'll simply select the first cfqq in the service tree. 1783 */ 1784static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) 1785{ 1786 struct cfq_rb_root *service_tree = 1787 service_tree_for(cfqd->serving_group, cfqd->serving_prio, 1788 cfqd->serving_type); 1789 1790 if (!cfqd->rq_queued) 1791 return NULL; 1792 1793 /* There is nothing to dispatch */ 1794 if (!service_tree) 1795 return NULL; 1796 if (RB_EMPTY_ROOT(&service_tree->rb)) 1797 return NULL; 1798 return cfq_rb_first(service_tree); 1799} 1800 1801static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd) 1802{ 1803 struct cfq_group *cfqg; 1804 struct cfq_queue *cfqq; 1805 int i, j; 1806 struct cfq_rb_root *st; 1807 1808 if (!cfqd->rq_queued) 1809 return NULL; 1810 1811 cfqg = cfq_get_next_cfqg(cfqd); 1812 if (!cfqg) 1813 return NULL; 1814 1815 for_each_cfqg_st(cfqg, i, j, st) 1816 if ((cfqq = cfq_rb_first(st)) != NULL) 1817 return cfqq; 1818 return NULL; 1819} 1820 1821/* 1822 * Get and set a new active queue for service. 1823 */ 1824static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd, 1825 struct cfq_queue *cfqq) 1826{ 1827 if (!cfqq) 1828 cfqq = cfq_get_next_queue(cfqd); 1829 1830 __cfq_set_active_queue(cfqd, cfqq); 1831 return cfqq; 1832} 1833 1834static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, 1835 struct request *rq) 1836{ 1837 if (blk_rq_pos(rq) >= cfqd->last_position) 1838 return blk_rq_pos(rq) - cfqd->last_position; 1839 else 1840 return cfqd->last_position - blk_rq_pos(rq); 1841} 1842 1843static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq, 1844 struct request *rq) 1845{ 1846 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR; 1847} 1848 1849static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, 1850 struct cfq_queue *cur_cfqq) 1851{ 1852 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio]; 1853 struct rb_node *parent, *node; 1854 struct cfq_queue *__cfqq; 1855 sector_t sector = cfqd->last_position; 1856 1857 if (RB_EMPTY_ROOT(root)) 1858 return NULL; 1859 1860 /* 1861 * First, if we find a request starting at the end of the last 1862 * request, choose it. 1863 */ 1864 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL); 1865 if (__cfqq) 1866 return __cfqq; 1867 1868 /* 1869 * If the exact sector wasn't found, the parent of the NULL leaf 1870 * will contain the closest sector. 1871 */ 1872 __cfqq = rb_entry(parent, struct cfq_queue, p_node); 1873 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) 1874 return __cfqq; 1875 1876 if (blk_rq_pos(__cfqq->next_rq) < sector) 1877 node = rb_next(&__cfqq->p_node); 1878 else 1879 node = rb_prev(&__cfqq->p_node); 1880 if (!node) 1881 return NULL; 1882 1883 __cfqq = rb_entry(node, struct cfq_queue, p_node); 1884 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) 1885 return __cfqq; 1886 1887 return NULL; 1888} 1889 1890/* 1891 * cfqd - obvious 1892 * cur_cfqq - passed in so that we don't decide that the current queue is 1893 * closely cooperating with itself. 1894 * 1895 * So, basically we're assuming that that cur_cfqq has dispatched at least 1896 * one request, and that cfqd->last_position reflects a position on the disk 1897 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid 1898 * assumption. 1899 */ 1900static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, 1901 struct cfq_queue *cur_cfqq) 1902{ 1903 struct cfq_queue *cfqq; 1904 1905 if (cfq_class_idle(cur_cfqq)) 1906 return NULL; 1907 if (!cfq_cfqq_sync(cur_cfqq)) 1908 return NULL; 1909 if (CFQQ_SEEKY(cur_cfqq)) 1910 return NULL; 1911 1912 /* 1913 * Don't search priority tree if it's the only queue in the group. 1914 */ 1915 if (cur_cfqq->cfqg->nr_cfqq == 1) 1916 return NULL; 1917 1918 /* 1919 * We should notice if some of the queues are cooperating, eg 1920 * working closely on the same area of the disk. In that case, 1921 * we can group them together and don't waste time idling. 1922 */ 1923 cfqq = cfqq_close(cfqd, cur_cfqq); 1924 if (!cfqq) 1925 return NULL; 1926 1927 /* If new queue belongs to different cfq_group, don't choose it */ 1928 if (cur_cfqq->cfqg != cfqq->cfqg) 1929 return NULL; 1930 1931 /* 1932 * It only makes sense to merge sync queues. 1933 */ 1934 if (!cfq_cfqq_sync(cfqq)) 1935 return NULL; 1936 if (CFQQ_SEEKY(cfqq)) 1937 return NULL; 1938 1939 /* 1940 * Do not merge queues of different priority classes 1941 */ 1942 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq)) 1943 return NULL; 1944 1945 return cfqq; 1946} 1947 1948/* 1949 * Determine whether we should enforce idle window for this queue. 1950 */ 1951 1952static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq) 1953{ 1954 enum wl_prio_t prio = cfqq_prio(cfqq); 1955 struct cfq_rb_root *service_tree = cfqq->service_tree; 1956 1957 BUG_ON(!service_tree); 1958 BUG_ON(!service_tree->count); 1959 1960 if (!cfqd->cfq_slice_idle) 1961 return false; 1962 1963 /* We never do for idle class queues. */ 1964 if (prio == IDLE_WORKLOAD) 1965 return false; 1966 1967 /* We do for queues that were marked with idle window flag. */ 1968 if (cfq_cfqq_idle_window(cfqq) && 1969 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)) 1970 return true; 1971 1972 /* 1973 * Otherwise, we do only if they are the last ones 1974 * in their service tree. 1975 */ 1976 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq)) 1977 return true; 1978 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", 1979 service_tree->count); 1980 return false; 1981} 1982 1983static void cfq_arm_slice_timer(struct cfq_data *cfqd) 1984{ 1985 struct cfq_queue *cfqq = cfqd->active_queue; 1986 struct cfq_io_context *cic; 1987 unsigned long sl, group_idle = 0; 1988 1989 /* 1990 * SSD device without seek penalty, disable idling. But only do so 1991 * for devices that support queuing, otherwise we still have a problem 1992 * with sync vs async workloads. 1993 */ 1994 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag) 1995 return; 1996 1997 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); 1998 WARN_ON(cfq_cfqq_slice_new(cfqq)); 1999 2000 /* 2001 * idle is disabled, either manually or by past process history 2002 */ 2003 if (!cfq_should_idle(cfqd, cfqq)) { 2004 /* no queue idling. Check for group idling */ 2005 if (cfqd->cfq_group_idle) 2006 group_idle = cfqd->cfq_group_idle; 2007 else 2008 return; 2009 } 2010 2011 /* 2012 * still active requests from this queue, don't idle 2013 */ 2014 if (cfqq->dispatched) 2015 return; 2016 2017 /* 2018 * task has exited, don't wait 2019 */ 2020 cic = cfqd->active_cic; 2021 if (!cic || !atomic_read(&cic->ioc->nr_tasks)) 2022 return; 2023 2024 /* 2025 * If our average think time is larger than the remaining time 2026 * slice, then don't idle. This avoids overrunning the allotted 2027 * time slice. 2028 */ 2029 if (sample_valid(cic->ttime_samples) && 2030 (cfqq->slice_end - jiffies < cic->ttime_mean)) { 2031 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%d", 2032 cic->ttime_mean); 2033 return; 2034 } 2035 2036 /* There are other queues in the group, don't do group idle */ 2037 if (group_idle && cfqq->cfqg->nr_cfqq > 1) 2038 return; 2039 2040 cfq_mark_cfqq_wait_request(cfqq); 2041 2042 if (group_idle) 2043 sl = cfqd->cfq_group_idle; 2044 else 2045 sl = cfqd->cfq_slice_idle; 2046 2047 mod_timer(&cfqd->idle_slice_timer, jiffies + sl); 2048 cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg); 2049 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl, 2050 group_idle ? 1 : 0); 2051} 2052 2053/* 2054 * Move request from internal lists to the request queue dispatch list. 2055 */ 2056static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) 2057{ 2058 struct cfq_data *cfqd = q->elevator->elevator_data; 2059 struct cfq_queue *cfqq = RQ_CFQQ(rq); 2060 2061 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert"); 2062 2063 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq); 2064 cfq_remove_request(rq); 2065 cfqq->dispatched++; 2066 (RQ_CFQG(rq))->dispatched++; 2067 elv_dispatch_sort(q, rq); 2068 2069 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++; 2070 cfqq->nr_sectors += blk_rq_sectors(rq); 2071 cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq), 2072 rq_data_dir(rq), rq_is_sync(rq)); 2073} 2074 2075/* 2076 * return expired entry, or NULL to just start from scratch in rbtree 2077 */ 2078static struct request *cfq_check_fifo(struct cfq_queue *cfqq) 2079{ 2080 struct request *rq = NULL; 2081 2082 if (cfq_cfqq_fifo_expire(cfqq)) 2083 return NULL; 2084 2085 cfq_mark_cfqq_fifo_expire(cfqq); 2086 2087 if (list_empty(&cfqq->fifo)) 2088 return NULL; 2089 2090 rq = rq_entry_fifo(cfqq->fifo.next); 2091 if (time_before(jiffies, rq_fifo_time(rq))) 2092 rq = NULL; 2093 2094 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq); 2095 return rq; 2096} 2097 2098static inline int 2099cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2100{ 2101 const int base_rq = cfqd->cfq_slice_async_rq; 2102 2103 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); 2104 2105 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); 2106} 2107 2108/* 2109 * Must be called with the queue_lock held. 2110 */ 2111static int cfqq_process_refs(struct cfq_queue *cfqq) 2112{ 2113 int process_refs, io_refs; 2114 2115 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE]; 2116 process_refs = cfqq->ref - io_refs; 2117 BUG_ON(process_refs < 0); 2118 return process_refs; 2119} 2120 2121static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) 2122{ 2123 int process_refs, new_process_refs; 2124 struct cfq_queue *__cfqq; 2125 2126 /* 2127 * If there are no process references on the new_cfqq, then it is 2128 * unsafe to follow the ->new_cfqq chain as other cfqq's in the 2129 * chain may have dropped their last reference (not just their 2130 * last process reference). 2131 */ 2132 if (!cfqq_process_refs(new_cfqq)) 2133 return; 2134 2135 /* Avoid a circular list and skip interim queue merges */ 2136 while ((__cfqq = new_cfqq->new_cfqq)) { 2137 if (__cfqq == cfqq) 2138 return; 2139 new_cfqq = __cfqq; 2140 } 2141 2142 process_refs = cfqq_process_refs(cfqq); 2143 new_process_refs = cfqq_process_refs(new_cfqq); 2144 /* 2145 * If the process for the cfqq has gone away, there is no 2146 * sense in merging the queues. 2147 */ 2148 if (process_refs == 0 || new_process_refs == 0) 2149 return; 2150 2151 /* 2152 * Merge in the direction of the lesser amount of work. 2153 */ 2154 if (new_process_refs >= process_refs) { 2155 cfqq->new_cfqq = new_cfqq; 2156 new_cfqq->ref += process_refs; 2157 } else { 2158 new_cfqq->new_cfqq = cfqq; 2159 cfqq->ref += new_process_refs; 2160 } 2161} 2162 2163static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, 2164 struct cfq_group *cfqg, enum wl_prio_t prio) 2165{ 2166 struct cfq_queue *queue; 2167 int i; 2168 bool key_valid = false; 2169 unsigned long lowest_key = 0; 2170 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD; 2171 2172 for (i = 0; i <= SYNC_WORKLOAD; ++i) { 2173 /* select the one with lowest rb_key */ 2174 queue = cfq_rb_first(service_tree_for(cfqg, prio, i)); 2175 if (queue && 2176 (!key_valid || time_before(queue->rb_key, lowest_key))) { 2177 lowest_key = queue->rb_key; 2178 cur_best = i; 2179 key_valid = true; 2180 } 2181 } 2182 2183 return cur_best; 2184} 2185 2186static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg) 2187{ 2188 unsigned slice; 2189 unsigned count; 2190 struct cfq_rb_root *st; 2191 unsigned group_slice; 2192 enum wl_prio_t original_prio = cfqd->serving_prio; 2193 2194 /* Choose next priority. RT > BE > IDLE */ 2195 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg)) 2196 cfqd->serving_prio = RT_WORKLOAD; 2197 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg)) 2198 cfqd->serving_prio = BE_WORKLOAD; 2199 else { 2200 cfqd->serving_prio = IDLE_WORKLOAD; 2201 cfqd->workload_expires = jiffies + 1; 2202 return; 2203 } 2204 2205 if (original_prio != cfqd->serving_prio) 2206 goto new_workload; 2207 2208 /* 2209 * For RT and BE, we have to choose also the type 2210 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload 2211 * expiration time 2212 */ 2213 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type); 2214 count = st->count; 2215 2216 /* 2217 * check workload expiration, and that we still have other queues ready 2218 */ 2219 if (count && !time_after(jiffies, cfqd->workload_expires)) 2220 return; 2221 2222new_workload: 2223 /* otherwise select new workload type */ 2224 cfqd->serving_type = 2225 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio); 2226 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type); 2227 count = st->count; 2228 2229 /* 2230 * the workload slice is computed as a fraction of target latency 2231 * proportional to the number of queues in that workload, over 2232 * all the queues in the same priority class 2233 */ 2234 group_slice = cfq_group_slice(cfqd, cfqg); 2235 2236 slice = group_slice * count / 2237 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio], 2238 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg)); 2239 2240 if (cfqd->serving_type == ASYNC_WORKLOAD) { 2241 unsigned int tmp; 2242 2243 /* 2244 * Async queues are currently system wide. Just taking 2245 * proportion of queues with-in same group will lead to higher 2246 * async ratio system wide as generally root group is going 2247 * to have higher weight. A more accurate thing would be to 2248 * calculate system wide asnc/sync ratio. 2249 */ 2250 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg); 2251 tmp = tmp/cfqd->busy_queues; 2252 slice = min_t(unsigned, slice, tmp); 2253 2254 /* async workload slice is scaled down according to 2255 * the sync/async slice ratio. */ 2256 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1]; 2257 } else 2258 /* sync workload slice is at least 2 * cfq_slice_idle */ 2259 slice = max(slice, 2 * cfqd->cfq_slice_idle); 2260 2261 slice = max_t(unsigned, slice, CFQ_MIN_TT); 2262 cfq_log(cfqd, "workload slice:%d", slice); 2263 cfqd->workload_expires = jiffies + slice; 2264} 2265 2266static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd) 2267{ 2268 struct cfq_rb_root *st = &cfqd->grp_service_tree; 2269 struct cfq_group *cfqg; 2270 2271 if (RB_EMPTY_ROOT(&st->rb)) 2272 return NULL; 2273 cfqg = cfq_rb_first_group(st); 2274 update_min_vdisktime(st); 2275 return cfqg; 2276} 2277 2278static void cfq_choose_cfqg(struct cfq_data *cfqd) 2279{ 2280 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd); 2281 2282 cfqd->serving_group = cfqg; 2283 2284 /* Restore the workload type data */ 2285 if (cfqg->saved_workload_slice) { 2286 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice; 2287 cfqd->serving_type = cfqg->saved_workload; 2288 cfqd->serving_prio = cfqg->saved_serving_prio; 2289 } else 2290 cfqd->workload_expires = jiffies - 1; 2291 2292 choose_service_tree(cfqd, cfqg); 2293} 2294 2295/* 2296 * Select a queue for service. If we have a current active queue, 2297 * check whether to continue servicing it, or retrieve and set a new one. 2298 */ 2299static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) 2300{ 2301 struct cfq_queue *cfqq, *new_cfqq = NULL; 2302 2303 cfqq = cfqd->active_queue; 2304 if (!cfqq) 2305 goto new_queue; 2306 2307 if (!cfqd->rq_queued) 2308 return NULL; 2309 2310 /* 2311 * We were waiting for group to get backlogged. Expire the queue 2312 */ 2313 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list)) 2314 goto expire; 2315 2316 /* 2317 * The active queue has run out of time, expire it and select new. 2318 */ 2319 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) { 2320 /* 2321 * If slice had not expired at the completion of last request 2322 * we might not have turned on wait_busy flag. Don't expire 2323 * the queue yet. Allow the group to get backlogged. 2324 * 2325 * The very fact that we have used the slice, that means we 2326 * have been idling all along on this queue and it should be 2327 * ok to wait for this request to complete. 2328 */ 2329 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list) 2330 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { 2331 cfqq = NULL; 2332 goto keep_queue; 2333 } else 2334 goto check_group_idle; 2335 } 2336 2337 /* 2338 * The active queue has requests and isn't expired, allow it to 2339 * dispatch. 2340 */ 2341 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 2342 goto keep_queue; 2343 2344 /* 2345 * If another queue has a request waiting within our mean seek 2346 * distance, let it run. The expire code will check for close 2347 * cooperators and put the close queue at the front of the service 2348 * tree. If possible, merge the expiring queue with the new cfqq. 2349 */ 2350 new_cfqq = cfq_close_cooperator(cfqd, cfqq); 2351 if (new_cfqq) { 2352 if (!cfqq->new_cfqq) 2353 cfq_setup_merge(cfqq, new_cfqq); 2354 goto expire; 2355 } 2356 2357 /* 2358 * No requests pending. If the active queue still has requests in 2359 * flight or is idling for a new request, allow either of these 2360 * conditions to happen (or time out) before selecting a new queue. 2361 */ 2362 if (timer_pending(&cfqd->idle_slice_timer)) { 2363 cfqq = NULL; 2364 goto keep_queue; 2365 } 2366 2367 /* 2368 * This is a deep seek queue, but the device is much faster than 2369 * the queue can deliver, don't idle 2370 **/ 2371 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) && 2372 (cfq_cfqq_slice_new(cfqq) || 2373 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) { 2374 cfq_clear_cfqq_deep(cfqq); 2375 cfq_clear_cfqq_idle_window(cfqq); 2376 } 2377 2378 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { 2379 cfqq = NULL; 2380 goto keep_queue; 2381 } 2382 2383 /* 2384 * If group idle is enabled and there are requests dispatched from 2385 * this group, wait for requests to complete. 2386 */ 2387check_group_idle: 2388 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 2389 && cfqq->cfqg->dispatched) { 2390 cfqq = NULL; 2391 goto keep_queue; 2392 } 2393 2394expire: 2395 cfq_slice_expired(cfqd, 0); 2396new_queue: 2397 /* 2398 * Current queue expired. Check if we have to switch to a new 2399 * service tree 2400 */ 2401 if (!new_cfqq) 2402 cfq_choose_cfqg(cfqd); 2403 2404 cfqq = cfq_set_active_queue(cfqd, new_cfqq); 2405keep_queue: 2406 return cfqq; 2407} 2408 2409static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) 2410{ 2411 int dispatched = 0; 2412 2413 while (cfqq->next_rq) { 2414 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); 2415 dispatched++; 2416 } 2417 2418 BUG_ON(!list_empty(&cfqq->fifo)); 2419 2420 /* By default cfqq is not expired if it is empty. Do it explicitly */ 2421 __cfq_slice_expired(cfqq->cfqd, cfqq, 0); 2422 return dispatched; 2423} 2424 2425/* 2426 * Drain our current requests. Used for barriers and when switching 2427 * io schedulers on-the-fly. 2428 */ 2429static int cfq_forced_dispatch(struct cfq_data *cfqd) 2430{ 2431 struct cfq_queue *cfqq; 2432 int dispatched = 0; 2433 2434 /* Expire the timeslice of the current active queue first */ 2435 cfq_slice_expired(cfqd, 0); 2436 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) { 2437 __cfq_set_active_queue(cfqd, cfqq); 2438 dispatched += __cfq_forced_dispatch_cfqq(cfqq); 2439 } 2440 2441 BUG_ON(cfqd->busy_queues); 2442 2443 cfq_log(cfqd, "forced_dispatch=%d", dispatched); 2444 return dispatched; 2445} 2446 2447static inline bool cfq_slice_used_soon(struct cfq_data *cfqd, 2448 struct cfq_queue *cfqq) 2449{ 2450 /* the queue hasn't finished any request, can't estimate */ 2451 if (cfq_cfqq_slice_new(cfqq)) 2452 return true; 2453 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched, 2454 cfqq->slice_end)) 2455 return true; 2456 2457 return false; 2458} 2459 2460static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2461{ 2462 unsigned int max_dispatch; 2463 2464 /* 2465 * Drain async requests before we start sync IO 2466 */ 2467 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC]) 2468 return false; 2469 2470 /* 2471 * If this is an async queue and we have sync IO in flight, let it wait 2472 */ 2473 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq)) 2474 return false; 2475 2476 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1); 2477 if (cfq_class_idle(cfqq)) 2478 max_dispatch = 1; 2479 2480 /* 2481 * Does this cfqq already have too much IO in flight? 2482 */ 2483 if (cfqq->dispatched >= max_dispatch) { 2484 bool promote_sync = false; 2485 /* 2486 * idle queue must always only have a single IO in flight 2487 */ 2488 if (cfq_class_idle(cfqq)) 2489 return false; 2490 2491 /* 2492 * If there is only one sync queue 2493 * we can ignore async queue here and give the sync 2494 * queue no dispatch limit. The reason is a sync queue can 2495 * preempt async queue, limiting the sync queue doesn't make 2496 * sense. This is useful for aiostress test. 2497 */ 2498 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1) 2499 promote_sync = true; 2500 2501 /* 2502 * We have other queues, don't allow more IO from this one 2503 */ 2504 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) && 2505 !promote_sync) 2506 return false; 2507 2508 /* 2509 * Sole queue user, no limit 2510 */ 2511 if (cfqd->busy_queues == 1 || promote_sync) 2512 max_dispatch = -1; 2513 else 2514 /* 2515 * Normally we start throttling cfqq when cfq_quantum/2 2516 * requests have been dispatched. But we can drive 2517 * deeper queue depths at the beginning of slice 2518 * subjected to upper limit of cfq_quantum. 2519 * */ 2520 max_dispatch = cfqd->cfq_quantum; 2521 } 2522 2523 /* 2524 * Async queues must wait a bit before being allowed dispatch. 2525 * We also ramp up the dispatch depth gradually for async IO, 2526 * based on the last sync IO we serviced 2527 */ 2528 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) { 2529 unsigned long last_sync = jiffies - cfqd->last_delayed_sync; 2530 unsigned int depth; 2531 2532 depth = last_sync / cfqd->cfq_slice[1]; 2533 if (!depth && !cfqq->dispatched) 2534 depth = 1; 2535 if (depth < max_dispatch) 2536 max_dispatch = depth; 2537 } 2538 2539 /* 2540 * If we're below the current max, allow a dispatch 2541 */ 2542 return cfqq->dispatched < max_dispatch; 2543} 2544 2545/* 2546 * Dispatch a request from cfqq, moving them to the request queue 2547 * dispatch list. 2548 */ 2549static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2550{ 2551 struct request *rq; 2552 2553 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); 2554 2555 if (!cfq_may_dispatch(cfqd, cfqq)) 2556 return false; 2557 2558 /* 2559 * follow expired path, else get first next available 2560 */ 2561 rq = cfq_check_fifo(cfqq); 2562 if (!rq) 2563 rq = cfqq->next_rq; 2564 2565 /* 2566 * insert request into driver dispatch list 2567 */ 2568 cfq_dispatch_insert(cfqd->queue, rq); 2569 2570 if (!cfqd->active_cic) { 2571 struct cfq_io_context *cic = RQ_CIC(rq); 2572 2573 atomic_long_inc(&cic->ioc->refcount); 2574 cfqd->active_cic = cic; 2575 } 2576 2577 return true; 2578} 2579 2580/* 2581 * Find the cfqq that we need to service and move a request from that to the 2582 * dispatch list 2583 */ 2584static int cfq_dispatch_requests(struct request_queue *q, int force) 2585{ 2586 struct cfq_data *cfqd = q->elevator->elevator_data; 2587 struct cfq_queue *cfqq; 2588 2589 if (!cfqd->busy_queues) 2590 return 0; 2591 2592 if (unlikely(force)) 2593 return cfq_forced_dispatch(cfqd); 2594 2595 cfqq = cfq_select_queue(cfqd); 2596 if (!cfqq) 2597 return 0; 2598 2599 /* 2600 * Dispatch a request from this cfqq, if it is allowed 2601 */ 2602 if (!cfq_dispatch_request(cfqd, cfqq)) 2603 return 0; 2604 2605 cfqq->slice_dispatch++; 2606 cfq_clear_cfqq_must_dispatch(cfqq); 2607 2608 /* 2609 * expire an async queue immediately if it has used up its slice. idle 2610 * queue always expire after 1 dispatch round. 2611 */ 2612 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && 2613 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) || 2614 cfq_class_idle(cfqq))) { 2615 cfqq->slice_end = jiffies + 1; 2616 cfq_slice_expired(cfqd, 0); 2617 } 2618 2619 cfq_log_cfqq(cfqd, cfqq, "dispatched a request"); 2620 return 1; 2621} 2622 2623/* 2624 * task holds one reference to the queue, dropped when task exits. each rq 2625 * in-flight on this queue also holds a reference, dropped when rq is freed. 2626 * 2627 * Each cfq queue took a reference on the parent group. Drop it now. 2628 * queue lock must be held here. 2629 */ 2630static void cfq_put_queue(struct cfq_queue *cfqq) 2631{ 2632 struct cfq_data *cfqd = cfqq->cfqd; 2633 struct cfq_group *cfqg; 2634 2635 BUG_ON(cfqq->ref <= 0); 2636 2637 cfqq->ref--; 2638 if (cfqq->ref) 2639 return; 2640 2641 cfq_log_cfqq(cfqd, cfqq, "put_queue"); 2642 BUG_ON(rb_first(&cfqq->sort_list)); 2643 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); 2644 cfqg = cfqq->cfqg; 2645 2646 if (unlikely(cfqd->active_queue == cfqq)) { 2647 __cfq_slice_expired(cfqd, cfqq, 0); 2648 cfq_schedule_dispatch(cfqd); 2649 } 2650 2651 BUG_ON(cfq_cfqq_on_rr(cfqq)); 2652 kmem_cache_free(cfq_pool, cfqq); 2653 cfq_put_cfqg(cfqg); 2654} 2655 2656/* 2657 * Call func for each cic attached to this ioc. 2658 */ 2659static void 2660call_for_each_cic(struct io_context *ioc, 2661 void (*func)(struct io_context *, struct cfq_io_context *)) 2662{ 2663 struct cfq_io_context *cic; 2664 struct hlist_node *n; 2665 2666 rcu_read_lock(); 2667 2668 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list) 2669 func(ioc, cic); 2670 2671 rcu_read_unlock(); 2672} 2673 2674static void cfq_cic_free_rcu(struct rcu_head *head) 2675{ 2676 struct cfq_io_context *cic; 2677 2678 cic = container_of(head, struct cfq_io_context, rcu_head); 2679 2680 kmem_cache_free(cfq_ioc_pool, cic); 2681 elv_ioc_count_dec(cfq_ioc_count); 2682 2683 if (ioc_gone) { 2684 /* 2685 * CFQ scheduler is exiting, grab exit lock and check 2686 * the pending io context count. If it hits zero, 2687 * complete ioc_gone and set it back to NULL 2688 */ 2689 spin_lock(&ioc_gone_lock); 2690 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) { 2691 complete(ioc_gone); 2692 ioc_gone = NULL; 2693 } 2694 spin_unlock(&ioc_gone_lock); 2695 } 2696} 2697 2698static void cfq_cic_free(struct cfq_io_context *cic) 2699{ 2700 call_rcu(&cic->rcu_head, cfq_cic_free_rcu); 2701} 2702 2703static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic) 2704{ 2705 unsigned long flags; 2706 unsigned long dead_key = (unsigned long) cic->key; 2707 2708 BUG_ON(!(dead_key & CIC_DEAD_KEY)); 2709 2710 spin_lock_irqsave(&ioc->lock, flags); 2711 radix_tree_delete(&ioc->radix_root, dead_key >> CIC_DEAD_INDEX_SHIFT); 2712 hlist_del_rcu(&cic->cic_list); 2713 spin_unlock_irqrestore(&ioc->lock, flags); 2714 2715 cfq_cic_free(cic); 2716} 2717 2718/* 2719 * Must be called with rcu_read_lock() held or preemption otherwise disabled. 2720 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(), 2721 * and ->trim() which is called with the task lock held 2722 */ 2723static void cfq_free_io_context(struct io_context *ioc) 2724{ 2725 /* 2726 * ioc->refcount is zero here, or we are called from elv_unregister(), 2727 * so no more cic's are allowed to be linked into this ioc. So it 2728 * should be ok to iterate over the known list, we will see all cic's 2729 * since no new ones are added. 2730 */ 2731 call_for_each_cic(ioc, cic_free_func); 2732} 2733 2734static void cfq_put_cooperator(struct cfq_queue *cfqq) 2735{ 2736 struct cfq_queue *__cfqq, *next; 2737 2738 /* 2739 * If this queue was scheduled to merge with another queue, be 2740 * sure to drop the reference taken on that queue (and others in 2741 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs. 2742 */ 2743 __cfqq = cfqq->new_cfqq; 2744 while (__cfqq) { 2745 if (__cfqq == cfqq) { 2746 WARN(1, "cfqq->new_cfqq loop detected\n"); 2747 break; 2748 } 2749 next = __cfqq->new_cfqq; 2750 cfq_put_queue(__cfqq); 2751 __cfqq = next; 2752 } 2753} 2754 2755static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) 2756{ 2757 if (unlikely(cfqq == cfqd->active_queue)) { 2758 __cfq_slice_expired(cfqd, cfqq, 0); 2759 cfq_schedule_dispatch(cfqd); 2760 } 2761 2762 cfq_put_cooperator(cfqq); 2763 2764 cfq_put_queue(cfqq); 2765} 2766 2767static void __cfq_exit_single_io_context(struct cfq_data *cfqd, 2768 struct cfq_io_context *cic) 2769{ 2770 struct io_context *ioc = cic->ioc; 2771 2772 list_del_init(&cic->queue_list); 2773 2774 /* 2775 * Make sure dead mark is seen for dead queues 2776 */ 2777 smp_wmb(); 2778 cic->key = cfqd_dead_key(cfqd); 2779 2780 if (ioc->ioc_data == cic) 2781 rcu_assign_pointer(ioc->ioc_data, NULL); 2782 2783 if (cic->cfqq[BLK_RW_ASYNC]) { 2784 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]); 2785 cic->cfqq[BLK_RW_ASYNC] = NULL; 2786 } 2787 2788 if (cic->cfqq[BLK_RW_SYNC]) { 2789 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]); 2790 cic->cfqq[BLK_RW_SYNC] = NULL; 2791 } 2792} 2793 2794static void cfq_exit_single_io_context(struct io_context *ioc, 2795 struct cfq_io_context *cic) 2796{ 2797 struct cfq_data *cfqd = cic_to_cfqd(cic); 2798 2799 if (cfqd) { 2800 struct request_queue *q = cfqd->queue; 2801 unsigned long flags; 2802 2803 spin_lock_irqsave(q->queue_lock, flags); 2804 2805 /* 2806 * Ensure we get a fresh copy of the ->key to prevent 2807 * race between exiting task and queue 2808 */ 2809 smp_read_barrier_depends(); 2810 if (cic->key == cfqd) 2811 __cfq_exit_single_io_context(cfqd, cic); 2812 2813 spin_unlock_irqrestore(q->queue_lock, flags); 2814 } 2815} 2816 2817/* 2818 * The process that ioc belongs to has exited, we need to clean up 2819 * and put the internal structures we have that belongs to that process. 2820 */ 2821static void cfq_exit_io_context(struct io_context *ioc) 2822{ 2823 call_for_each_cic(ioc, cfq_exit_single_io_context); 2824} 2825 2826static struct cfq_io_context * 2827cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) 2828{ 2829 struct cfq_io_context *cic; 2830 2831 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO, 2832 cfqd->queue->node); 2833 if (cic) { 2834 cic->last_end_request = jiffies; 2835 INIT_LIST_HEAD(&cic->queue_list); 2836 INIT_HLIST_NODE(&cic->cic_list); 2837 cic->dtor = cfq_free_io_context; 2838 cic->exit = cfq_exit_io_context; 2839 elv_ioc_count_inc(cfq_ioc_count); 2840 } 2841 2842 return cic; 2843} 2844 2845static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) 2846{ 2847 struct task_struct *tsk = current; 2848 int ioprio_class; 2849 2850 if (!cfq_cfqq_prio_changed(cfqq)) 2851 return; 2852 2853 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio); 2854 switch (ioprio_class) { 2855 default: 2856 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); 2857 case IOPRIO_CLASS_NONE: 2858 /* 2859 * no prio set, inherit CPU scheduling settings 2860 */ 2861 cfqq->ioprio = task_nice_ioprio(tsk); 2862 cfqq->ioprio_class = task_nice_ioclass(tsk); 2863 break; 2864 case IOPRIO_CLASS_RT: 2865 cfqq->ioprio = task_ioprio(ioc); 2866 cfqq->ioprio_class = IOPRIO_CLASS_RT; 2867 break; 2868 case IOPRIO_CLASS_BE: 2869 cfqq->ioprio = task_ioprio(ioc); 2870 cfqq->ioprio_class = IOPRIO_CLASS_BE; 2871 break; 2872 case IOPRIO_CLASS_IDLE: 2873 cfqq->ioprio_class = IOPRIO_CLASS_IDLE; 2874 cfqq->ioprio = 7; 2875 cfq_clear_cfqq_idle_window(cfqq); 2876 break; 2877 } 2878 2879 /* 2880 * keep track of original prio settings in case we have to temporarily 2881 * elevate the priority of this queue 2882 */ 2883 cfqq->org_ioprio = cfqq->ioprio; 2884 cfqq->org_ioprio_class = cfqq->ioprio_class; 2885 cfq_clear_cfqq_prio_changed(cfqq); 2886} 2887 2888static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic) 2889{ 2890 struct cfq_data *cfqd = cic_to_cfqd(cic); 2891 struct cfq_queue *cfqq; 2892 unsigned long flags; 2893 2894 if (unlikely(!cfqd)) 2895 return; 2896 2897 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 2898 2899 cfqq = cic->cfqq[BLK_RW_ASYNC]; 2900 if (cfqq) { 2901 struct cfq_queue *new_cfqq; 2902 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc, 2903 GFP_ATOMIC); 2904 if (new_cfqq) { 2905 cic->cfqq[BLK_RW_ASYNC] = new_cfqq; 2906 cfq_put_queue(cfqq); 2907 } 2908 } 2909 2910 cfqq = cic->cfqq[BLK_RW_SYNC]; 2911 if (cfqq) 2912 cfq_mark_cfqq_prio_changed(cfqq); 2913 2914 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 2915} 2916 2917static void cfq_ioc_set_ioprio(struct io_context *ioc) 2918{ 2919 call_for_each_cic(ioc, changed_ioprio); 2920 ioc->ioprio_changed = 0; 2921} 2922 2923static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, 2924 pid_t pid, bool is_sync) 2925{ 2926 RB_CLEAR_NODE(&cfqq->rb_node); 2927 RB_CLEAR_NODE(&cfqq->p_node); 2928 INIT_LIST_HEAD(&cfqq->fifo); 2929 2930 cfqq->ref = 0; 2931 cfqq->cfqd = cfqd; 2932 2933 cfq_mark_cfqq_prio_changed(cfqq); 2934 2935 if (is_sync) { 2936 if (!cfq_class_idle(cfqq)) 2937 cfq_mark_cfqq_idle_window(cfqq); 2938 cfq_mark_cfqq_sync(cfqq); 2939 } 2940 cfqq->pid = pid; 2941} 2942 2943#ifdef CONFIG_CFQ_GROUP_IOSCHED 2944static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic) 2945{ 2946 struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1); 2947 struct cfq_data *cfqd = cic_to_cfqd(cic); 2948 unsigned long flags; 2949 struct request_queue *q; 2950 2951 if (unlikely(!cfqd)) 2952 return; 2953 2954 q = cfqd->queue; 2955 2956 spin_lock_irqsave(q->queue_lock, flags); 2957 2958 if (sync_cfqq) { 2959 /* 2960 * Drop reference to sync queue. A new sync queue will be 2961 * assigned in new group upon arrival of a fresh request. 2962 */ 2963 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup"); 2964 cic_set_cfqq(cic, NULL, 1); 2965 cfq_put_queue(sync_cfqq); 2966 } 2967 2968 spin_unlock_irqrestore(q->queue_lock, flags); 2969} 2970 2971static void cfq_ioc_set_cgroup(struct io_context *ioc) 2972{ 2973 call_for_each_cic(ioc, changed_cgroup); 2974 ioc->cgroup_changed = 0; 2975} 2976#endif /* CONFIG_CFQ_GROUP_IOSCHED */ 2977 2978static struct cfq_queue * 2979cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, 2980 struct io_context *ioc, gfp_t gfp_mask) 2981{ 2982 struct cfq_queue *cfqq, *new_cfqq = NULL; 2983 struct cfq_io_context *cic; 2984 struct cfq_group *cfqg; 2985 2986retry: 2987 cfqg = cfq_get_cfqg(cfqd); 2988 cic = cfq_cic_lookup(cfqd, ioc); 2989 /* cic always exists here */ 2990 cfqq = cic_to_cfqq(cic, is_sync); 2991 2992 /* 2993 * Always try a new alloc if we fell back to the OOM cfqq 2994 * originally, since it should just be a temporary situation. 2995 */ 2996 if (!cfqq || cfqq == &cfqd->oom_cfqq) { 2997 cfqq = NULL; 2998 if (new_cfqq) { 2999 cfqq = new_cfqq; 3000 new_cfqq = NULL; 3001 } else if (gfp_mask & __GFP_WAIT) { 3002 spin_unlock_irq(cfqd->queue->queue_lock); 3003 new_cfqq = kmem_cache_alloc_node(cfq_pool, 3004 gfp_mask | __GFP_ZERO, 3005 cfqd->queue->node); 3006 spin_lock_irq(cfqd->queue->queue_lock); 3007 if (new_cfqq) 3008 goto retry; 3009 } else { 3010 cfqq = kmem_cache_alloc_node(cfq_pool, 3011 gfp_mask | __GFP_ZERO, 3012 cfqd->queue->node); 3013 } 3014 3015 if (cfqq) { 3016 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync); 3017 cfq_init_prio_data(cfqq, ioc); 3018 cfq_link_cfqq_cfqg(cfqq, cfqg); 3019 cfq_log_cfqq(cfqd, cfqq, "alloced"); 3020 } else 3021 cfqq = &cfqd->oom_cfqq; 3022 } 3023 3024 if (new_cfqq) 3025 kmem_cache_free(cfq_pool, new_cfqq); 3026 3027 return cfqq; 3028} 3029 3030static struct cfq_queue ** 3031cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) 3032{ 3033 switch (ioprio_class) { 3034 case IOPRIO_CLASS_RT: 3035 return &cfqd->async_cfqq[0][ioprio]; 3036 case IOPRIO_CLASS_BE: 3037 return &cfqd->async_cfqq[1][ioprio]; 3038 case IOPRIO_CLASS_IDLE: 3039 return &cfqd->async_idle_cfqq; 3040 default: 3041 BUG(); 3042 } 3043} 3044 3045static struct cfq_queue * 3046cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc, 3047 gfp_t gfp_mask) 3048{ 3049 const int ioprio = task_ioprio(ioc); 3050 const int ioprio_class = task_ioprio_class(ioc); 3051 struct cfq_queue **async_cfqq = NULL; 3052 struct cfq_queue *cfqq = NULL; 3053 3054 if (!is_sync) { 3055 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); 3056 cfqq = *async_cfqq; 3057 } 3058 3059 if (!cfqq) 3060 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask); 3061 3062 /* 3063 * pin the queue now that it's allocated, scheduler exit will prune it 3064 */ 3065 if (!is_sync && !(*async_cfqq)) { 3066 cfqq->ref++; 3067 *async_cfqq = cfqq; 3068 } 3069 3070 cfqq->ref++; 3071 return cfqq; 3072} 3073 3074/* 3075 * We drop cfq io contexts lazily, so we may find a dead one. 3076 */ 3077static void 3078cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc, 3079 struct cfq_io_context *cic) 3080{ 3081 unsigned long flags; 3082 3083 WARN_ON(!list_empty(&cic->queue_list)); 3084 BUG_ON(cic->key != cfqd_dead_key(cfqd)); 3085 3086 spin_lock_irqsave(&ioc->lock, flags); 3087 3088 BUG_ON(ioc->ioc_data == cic); 3089 3090 radix_tree_delete(&ioc->radix_root, cfqd->cic_index); 3091 hlist_del_rcu(&cic->cic_list); 3092 spin_unlock_irqrestore(&ioc->lock, flags); 3093 3094 cfq_cic_free(cic); 3095} 3096 3097static struct cfq_io_context * 3098cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc) 3099{ 3100 struct cfq_io_context *cic; 3101 unsigned long flags; 3102 3103 if (unlikely(!ioc)) 3104 return NULL; 3105 3106 rcu_read_lock(); 3107 3108 /* 3109 * we maintain a last-hit cache, to avoid browsing over the tree 3110 */ 3111 cic = rcu_dereference(ioc->ioc_data); 3112 if (cic && cic->key == cfqd) { 3113 rcu_read_unlock(); 3114 return cic; 3115 } 3116 3117 do { 3118 cic = radix_tree_lookup(&ioc->radix_root, cfqd->cic_index); 3119 rcu_read_unlock(); 3120 if (!cic) 3121 break; 3122 if (unlikely(cic->key != cfqd)) { 3123 cfq_drop_dead_cic(cfqd, ioc, cic); 3124 rcu_read_lock(); 3125 continue; 3126 } 3127 3128 spin_lock_irqsave(&ioc->lock, flags); 3129 rcu_assign_pointer(ioc->ioc_data, cic); 3130 spin_unlock_irqrestore(&ioc->lock, flags); 3131 break; 3132 } while (1); 3133 3134 return cic; 3135} 3136 3137/* 3138 * Add cic into ioc, using cfqd as the search key. This enables us to lookup 3139 * the process specific cfq io context when entered from the block layer. 3140 * Also adds the cic to a per-cfqd list, used when this queue is removed. 3141 */ 3142static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, 3143 struct cfq_io_context *cic, gfp_t gfp_mask) 3144{ 3145 unsigned long flags; 3146 int ret; 3147 3148 ret = radix_tree_preload(gfp_mask); 3149 if (!ret) { 3150 cic->ioc = ioc; 3151 cic->key = cfqd; 3152 3153 spin_lock_irqsave(&ioc->lock, flags); 3154 ret = radix_tree_insert(&ioc->radix_root, 3155 cfqd->cic_index, cic); 3156 if (!ret) 3157 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list); 3158 spin_unlock_irqrestore(&ioc->lock, flags); 3159 3160 radix_tree_preload_end(); 3161 3162 if (!ret) { 3163 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 3164 list_add(&cic->queue_list, &cfqd->cic_list); 3165 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 3166 } 3167 } 3168 3169 if (ret) 3170 printk(KERN_ERR "cfq: cic link failed!\n"); 3171 3172 return ret; 3173} 3174 3175/* 3176 * Setup general io context and cfq io context. There can be several cfq 3177 * io contexts per general io context, if this process is doing io to more 3178 * than one device managed by cfq. 3179 */ 3180static struct cfq_io_context * 3181cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) 3182{ 3183 struct io_context *ioc = NULL; 3184 struct cfq_io_context *cic; 3185 3186 might_sleep_if(gfp_mask & __GFP_WAIT); 3187 3188 ioc = get_io_context(gfp_mask, cfqd->queue->node); 3189 if (!ioc) 3190 return NULL; 3191 3192 cic = cfq_cic_lookup(cfqd, ioc); 3193 if (cic) 3194 goto out; 3195 3196 cic = cfq_alloc_io_context(cfqd, gfp_mask); 3197 if (cic == NULL) 3198 goto err; 3199 3200 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask)) 3201 goto err_free; 3202 3203out: 3204 smp_read_barrier_depends(); 3205 if (unlikely(ioc->ioprio_changed)) 3206 cfq_ioc_set_ioprio(ioc); 3207 3208#ifdef CONFIG_CFQ_GROUP_IOSCHED 3209 if (unlikely(ioc->cgroup_changed)) 3210 cfq_ioc_set_cgroup(ioc); 3211#endif 3212 return cic; 3213err_free: 3214 cfq_cic_free(cic); 3215err: 3216 put_io_context(ioc); 3217 return NULL; 3218} 3219 3220static void 3221cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) 3222{ 3223 unsigned long elapsed = jiffies - cic->last_end_request; 3224 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); 3225 3226 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; 3227 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; 3228 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; 3229} 3230 3231static void 3232cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3233 struct request *rq) 3234{ 3235 sector_t sdist = 0; 3236 sector_t n_sec = blk_rq_sectors(rq); 3237 if (cfqq->last_request_pos) { 3238 if (cfqq->last_request_pos < blk_rq_pos(rq)) 3239 sdist = blk_rq_pos(rq) - cfqq->last_request_pos; 3240 else 3241 sdist = cfqq->last_request_pos - blk_rq_pos(rq); 3242 } 3243 3244 cfqq->seek_history <<= 1; 3245 if (blk_queue_nonrot(cfqd->queue)) 3246 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT); 3247 else 3248 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR); 3249} 3250 3251/* 3252 * Disable idle window if the process thinks too long or seeks so much that 3253 * it doesn't matter 3254 */ 3255static void 3256cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3257 struct cfq_io_context *cic) 3258{ 3259 int old_idle, enable_idle; 3260 3261 /* 3262 * Don't idle for async or idle io prio class 3263 */ 3264 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq)) 3265 return; 3266 3267 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); 3268 3269 if (cfqq->queued[0] + cfqq->queued[1] >= 4) 3270 cfq_mark_cfqq_deep(cfqq); 3271 3272 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE)) 3273 enable_idle = 0; 3274 else if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || 3275 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq))) 3276 enable_idle = 0; 3277 else if (sample_valid(cic->ttime_samples)) { 3278 if (cic->ttime_mean > cfqd->cfq_slice_idle) 3279 enable_idle = 0; 3280 else 3281 enable_idle = 1; 3282 } 3283 3284 if (old_idle != enable_idle) { 3285 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle); 3286 if (enable_idle) 3287 cfq_mark_cfqq_idle_window(cfqq); 3288 else 3289 cfq_clear_cfqq_idle_window(cfqq); 3290 } 3291} 3292 3293/* 3294 * Check if new_cfqq should preempt the currently active queue. Return 0 for 3295 * no or if we aren't sure, a 1 will cause a preempt. 3296 */ 3297static bool 3298cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, 3299 struct request *rq) 3300{ 3301 struct cfq_queue *cfqq; 3302 3303 cfqq = cfqd->active_queue; 3304 if (!cfqq) 3305 return false; 3306 3307 if (cfq_class_idle(new_cfqq)) 3308 return false; 3309 3310 if (cfq_class_idle(cfqq)) 3311 return true; 3312 3313 /* 3314 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice. 3315 */ 3316 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq)) 3317 return false; 3318 3319 /* 3320 * if the new request is sync, but the currently running queue is 3321 * not, let the sync request have priority. 3322 */ 3323 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) 3324 return true; 3325 3326 if (new_cfqq->cfqg != cfqq->cfqg) 3327 return false; 3328 3329 if (cfq_slice_used(cfqq)) 3330 return true; 3331 3332 /* Allow preemption only if we are idling on sync-noidle tree */ 3333 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD && 3334 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD && 3335 new_cfqq->service_tree->count == 2 && 3336 RB_EMPTY_ROOT(&cfqq->sort_list)) 3337 return true; 3338 3339 /* 3340 * So both queues are sync. Let the new request get disk time if 3341 * it's a metadata request and the current queue is doing regular IO. 3342 */ 3343 if ((rq->cmd_flags & REQ_META) && !cfqq->meta_pending) 3344 return true; 3345 3346 /* 3347 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice. 3348 */ 3349 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq)) 3350 return true; 3351 3352 /* An idle queue should not be idle now for some reason */ 3353 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq)) 3354 return true; 3355 3356 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) 3357 return false; 3358 3359 /* 3360 * if this request is as-good as one we would expect from the 3361 * current cfqq, let it preempt 3362 */ 3363 if (cfq_rq_close(cfqd, cfqq, rq)) 3364 return true; 3365 3366 return false; 3367} 3368 3369/* 3370 * cfqq preempts the active queue. if we allowed preempt with no slice left, 3371 * let it have half of its nominal slice. 3372 */ 3373static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3374{ 3375 struct cfq_queue *old_cfqq = cfqd->active_queue; 3376 3377 cfq_log_cfqq(cfqd, cfqq, "preempt"); 3378 cfq_slice_expired(cfqd, 1); 3379 3380 /* 3381 * workload type is changed, don't save slice, otherwise preempt 3382 * doesn't happen 3383 */ 3384 if (cfqq_type(old_cfqq) != cfqq_type(cfqq)) 3385 cfqq->cfqg->saved_workload_slice = 0; 3386 3387 /* 3388 * Put the new queue at the front of the of the current list, 3389 * so we know that it will be selected next. 3390 */ 3391 BUG_ON(!cfq_cfqq_on_rr(cfqq)); 3392 3393 cfq_service_tree_add(cfqd, cfqq, 1); 3394 3395 cfqq->slice_end = 0; 3396 cfq_mark_cfqq_slice_new(cfqq); 3397} 3398 3399/* 3400 * Called when a new fs request (rq) is added (to cfqq). Check if there's 3401 * something we should do about it 3402 */ 3403static void 3404cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, 3405 struct request *rq) 3406{ 3407 struct cfq_io_context *cic = RQ_CIC(rq); 3408 3409 cfqd->rq_queued++; 3410 if (rq->cmd_flags & REQ_META) 3411 cfqq->meta_pending++; 3412 3413 cfq_update_io_thinktime(cfqd, cic); 3414 cfq_update_io_seektime(cfqd, cfqq, rq); 3415 cfq_update_idle_window(cfqd, cfqq, cic); 3416 3417 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); 3418 3419 if (cfqq == cfqd->active_queue) { 3420 /* 3421 * Remember that we saw a request from this process, but 3422 * don't start queuing just yet. Otherwise we risk seeing lots 3423 * of tiny requests, because we disrupt the normal plugging 3424 * and merging. If the request is already larger than a single 3425 * page, let it rip immediately. For that case we assume that 3426 * merging is already done. Ditto for a busy system that 3427 * has other work pending, don't risk delaying until the 3428 * idle timer unplug to continue working. 3429 */ 3430 if (cfq_cfqq_wait_request(cfqq)) { 3431 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE || 3432 cfqd->busy_queues > 1) { 3433 cfq_del_timer(cfqd, cfqq); 3434 cfq_clear_cfqq_wait_request(cfqq); 3435 __blk_run_queue(cfqd->queue); 3436 } else { 3437 cfq_blkiocg_update_idle_time_stats( 3438 &cfqq->cfqg->blkg); 3439 cfq_mark_cfqq_must_dispatch(cfqq); 3440 } 3441 } 3442 } else if (cfq_should_preempt(cfqd, cfqq, rq)) { 3443 /* 3444 * not the active queue - expire current slice if it is 3445 * idle and has expired it's mean thinktime or this new queue 3446 * has some old slice time left and is of higher priority or 3447 * this new queue is RT and the current one is BE 3448 */ 3449 cfq_preempt_queue(cfqd, cfqq); 3450 __blk_run_queue(cfqd->queue); 3451 } 3452} 3453 3454static void cfq_insert_request(struct request_queue *q, struct request *rq) 3455{ 3456 struct cfq_data *cfqd = q->elevator->elevator_data; 3457 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3458 3459 cfq_log_cfqq(cfqd, cfqq, "insert_request"); 3460 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc); 3461 3462 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]); 3463 list_add_tail(&rq->queuelist, &cfqq->fifo); 3464 cfq_add_rq_rb(rq); 3465 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg, 3466 &cfqd->serving_group->blkg, rq_data_dir(rq), 3467 rq_is_sync(rq)); 3468 cfq_rq_enqueued(cfqd, cfqq, rq); 3469} 3470 3471/* 3472 * Update hw_tag based on peak queue depth over 50 samples under 3473 * sufficient load. 3474 */ 3475static void cfq_update_hw_tag(struct cfq_data *cfqd) 3476{ 3477 struct cfq_queue *cfqq = cfqd->active_queue; 3478 3479 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth) 3480 cfqd->hw_tag_est_depth = cfqd->rq_in_driver; 3481 3482 if (cfqd->hw_tag == 1) 3483 return; 3484 3485 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN && 3486 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN) 3487 return; 3488 3489 /* 3490 * If active queue hasn't enough requests and can idle, cfq might not 3491 * dispatch sufficient requests to hardware. Don't zero hw_tag in this 3492 * case 3493 */ 3494 if (cfqq && cfq_cfqq_idle_window(cfqq) && 3495 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] < 3496 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN) 3497 return; 3498 3499 if (cfqd->hw_tag_samples++ < 50) 3500 return; 3501 3502 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN) 3503 cfqd->hw_tag = 1; 3504 else 3505 cfqd->hw_tag = 0; 3506} 3507 3508static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq) 3509{ 3510 struct cfq_io_context *cic = cfqd->active_cic; 3511 3512 /* If the queue already has requests, don't wait */ 3513 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 3514 return false; 3515 3516 /* If there are other queues in the group, don't wait */ 3517 if (cfqq->cfqg->nr_cfqq > 1) 3518 return false; 3519 3520 if (cfq_slice_used(cfqq)) 3521 return true; 3522 3523 /* if slice left is less than think time, wait busy */ 3524 if (cic && sample_valid(cic->ttime_samples) 3525 && (cfqq->slice_end - jiffies < cic->ttime_mean)) 3526 return true; 3527 3528 /* 3529 * If think times is less than a jiffy than ttime_mean=0 and above 3530 * will not be true. It might happen that slice has not expired yet 3531 * but will expire soon (4-5 ns) during select_queue(). To cover the 3532 * case where think time is less than a jiffy, mark the queue wait 3533 * busy if only 1 jiffy is left in the slice. 3534 */ 3535 if (cfqq->slice_end - jiffies == 1) 3536 return true; 3537 3538 return false; 3539} 3540 3541static void cfq_completed_request(struct request_queue *q, struct request *rq) 3542{ 3543 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3544 struct cfq_data *cfqd = cfqq->cfqd; 3545 const int sync = rq_is_sync(rq); 3546 unsigned long now; 3547 3548 now = jiffies; 3549 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d", 3550 !!(rq->cmd_flags & REQ_NOIDLE)); 3551 3552 cfq_update_hw_tag(cfqd); 3553 3554 WARN_ON(!cfqd->rq_in_driver); 3555 WARN_ON(!cfqq->dispatched); 3556 cfqd->rq_in_driver--; 3557 cfqq->dispatched--; 3558 (RQ_CFQG(rq))->dispatched--; 3559 cfq_blkiocg_update_completion_stats(&cfqq->cfqg->blkg, 3560 rq_start_time_ns(rq), rq_io_start_time_ns(rq), 3561 rq_data_dir(rq), rq_is_sync(rq)); 3562 3563 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--; 3564 3565 if (sync) { 3566 RQ_CIC(rq)->last_end_request = now; 3567 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now)) 3568 cfqd->last_delayed_sync = now; 3569 } 3570 3571 /* 3572 * If this is the active queue, check if it needs to be expired, 3573 * or if we want to idle in case it has no pending requests. 3574 */ 3575 if (cfqd->active_queue == cfqq) { 3576 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list); 3577 3578 if (cfq_cfqq_slice_new(cfqq)) { 3579 cfq_set_prio_slice(cfqd, cfqq); 3580 cfq_clear_cfqq_slice_new(cfqq); 3581 } 3582 3583 /* 3584 * Should we wait for next request to come in before we expire 3585 * the queue. 3586 */ 3587 if (cfq_should_wait_busy(cfqd, cfqq)) { 3588 unsigned long extend_sl = cfqd->cfq_slice_idle; 3589 if (!cfqd->cfq_slice_idle) 3590 extend_sl = cfqd->cfq_group_idle; 3591 cfqq->slice_end = jiffies + extend_sl; 3592 cfq_mark_cfqq_wait_busy(cfqq); 3593 cfq_log_cfqq(cfqd, cfqq, "will busy wait"); 3594 } 3595 3596 /* 3597 * Idling is not enabled on: 3598 * - expired queues 3599 * - idle-priority queues 3600 * - async queues 3601 * - queues with still some requests queued 3602 * - when there is a close cooperator 3603 */ 3604 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq)) 3605 cfq_slice_expired(cfqd, 1); 3606 else if (sync && cfqq_empty && 3607 !cfq_close_cooperator(cfqd, cfqq)) { 3608 cfq_arm_slice_timer(cfqd); 3609 } 3610 } 3611 3612 if (!cfqd->rq_in_driver) 3613 cfq_schedule_dispatch(cfqd); 3614} 3615 3616/* 3617 * we temporarily boost lower priority queues if they are holding fs exclusive 3618 * resources. they are boosted to normal prio (CLASS_BE/4) 3619 */ 3620static void cfq_prio_boost(struct cfq_queue *cfqq) 3621{ 3622 if (has_fs_excl()) { 3623 /* 3624 * boost idle prio on transactions that would lock out other 3625 * users of the filesystem 3626 */ 3627 if (cfq_class_idle(cfqq)) 3628 cfqq->ioprio_class = IOPRIO_CLASS_BE; 3629 if (cfqq->ioprio > IOPRIO_NORM) 3630 cfqq->ioprio = IOPRIO_NORM; 3631 } else { 3632 /* 3633 * unboost the queue (if needed) 3634 */ 3635 cfqq->ioprio_class = cfqq->org_ioprio_class; 3636 cfqq->ioprio = cfqq->org_ioprio; 3637 } 3638} 3639 3640static inline int __cfq_may_queue(struct cfq_queue *cfqq) 3641{ 3642 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) { 3643 cfq_mark_cfqq_must_alloc_slice(cfqq); 3644 return ELV_MQUEUE_MUST; 3645 } 3646 3647 return ELV_MQUEUE_MAY; 3648} 3649 3650static int cfq_may_queue(struct request_queue *q, int rw) 3651{ 3652 struct cfq_data *cfqd = q->elevator->elevator_data; 3653 struct task_struct *tsk = current; 3654 struct cfq_io_context *cic; 3655 struct cfq_queue *cfqq; 3656 3657 /* 3658 * don't force setup of a queue from here, as a call to may_queue 3659 * does not necessarily imply that a request actually will be queued. 3660 * so just lookup a possibly existing queue, or return 'may queue' 3661 * if that fails 3662 */ 3663 cic = cfq_cic_lookup(cfqd, tsk->io_context); 3664 if (!cic) 3665 return ELV_MQUEUE_MAY; 3666 3667 cfqq = cic_to_cfqq(cic, rw_is_sync(rw)); 3668 if (cfqq) { 3669 cfq_init_prio_data(cfqq, cic->ioc); 3670 cfq_prio_boost(cfqq); 3671 3672 return __cfq_may_queue(cfqq); 3673 } 3674 3675 return ELV_MQUEUE_MAY; 3676} 3677 3678/* 3679 * queue lock held here 3680 */ 3681static void cfq_put_request(struct request *rq) 3682{ 3683 struct cfq_queue *cfqq = RQ_CFQQ(rq); 3684 3685 if (cfqq) { 3686 const int rw = rq_data_dir(rq); 3687 3688 BUG_ON(!cfqq->allocated[rw]); 3689 cfqq->allocated[rw]--; 3690 3691 put_io_context(RQ_CIC(rq)->ioc); 3692 3693 rq->elevator_private[0] = NULL; 3694 rq->elevator_private[1] = NULL; 3695 3696 /* Put down rq reference on cfqg */ 3697 cfq_put_cfqg(RQ_CFQG(rq)); 3698 rq->elevator_private[2] = NULL; 3699 3700 cfq_put_queue(cfqq); 3701 } 3702} 3703 3704static struct cfq_queue * 3705cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic, 3706 struct cfq_queue *cfqq) 3707{ 3708 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq); 3709 cic_set_cfqq(cic, cfqq->new_cfqq, 1); 3710 cfq_mark_cfqq_coop(cfqq->new_cfqq); 3711 cfq_put_queue(cfqq); 3712 return cic_to_cfqq(cic, 1); 3713} 3714 3715/* 3716 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this 3717 * was the last process referring to said cfqq. 3718 */ 3719static struct cfq_queue * 3720split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq) 3721{ 3722 if (cfqq_process_refs(cfqq) == 1) { 3723 cfqq->pid = current->pid; 3724 cfq_clear_cfqq_coop(cfqq); 3725 cfq_clear_cfqq_split_coop(cfqq); 3726 return cfqq; 3727 } 3728 3729 cic_set_cfqq(cic, NULL, 1); 3730 3731 cfq_put_cooperator(cfqq); 3732 3733 cfq_put_queue(cfqq); 3734 return NULL; 3735} 3736/* 3737 * Allocate cfq data structures associated with this request. 3738 */ 3739static int 3740cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) 3741{ 3742 struct cfq_data *cfqd = q->elevator->elevator_data; 3743 struct cfq_io_context *cic; 3744 const int rw = rq_data_dir(rq); 3745 const bool is_sync = rq_is_sync(rq); 3746 struct cfq_queue *cfqq; 3747 unsigned long flags; 3748 3749 might_sleep_if(gfp_mask & __GFP_WAIT); 3750 3751 cic = cfq_get_io_context(cfqd, gfp_mask); 3752 3753 spin_lock_irqsave(q->queue_lock, flags); 3754 3755 if (!cic) 3756 goto queue_fail; 3757 3758new_queue: 3759 cfqq = cic_to_cfqq(cic, is_sync); 3760 if (!cfqq || cfqq == &cfqd->oom_cfqq) { 3761 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask); 3762 cic_set_cfqq(cic, cfqq, is_sync); 3763 } else { 3764 /* 3765 * If the queue was seeky for too long, break it apart. 3766 */ 3767 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) { 3768 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq"); 3769 cfqq = split_cfqq(cic, cfqq); 3770 if (!cfqq) 3771 goto new_queue; 3772 } 3773 3774 /* 3775 * Check to see if this queue is scheduled to merge with 3776 * another, closely cooperating queue. The merging of 3777 * queues happens here as it must be done in process context. 3778 * The reference on new_cfqq was taken in merge_cfqqs. 3779 */ 3780 if (cfqq->new_cfqq) 3781 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq); 3782 } 3783 3784 cfqq->allocated[rw]++; 3785 3786 cfqq->ref++; 3787 rq->elevator_private[0] = cic; 3788 rq->elevator_private[1] = cfqq; 3789 rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg); 3790 spin_unlock_irqrestore(q->queue_lock, flags); 3791 return 0; 3792 3793queue_fail: 3794 if (cic) 3795 put_io_context(cic->ioc); 3796 3797 cfq_schedule_dispatch(cfqd); 3798 spin_unlock_irqrestore(q->queue_lock, flags); 3799 cfq_log(cfqd, "set_request fail"); 3800 return 1; 3801} 3802 3803static void cfq_kick_queue(struct work_struct *work) 3804{ 3805 struct cfq_data *cfqd = 3806 container_of(work, struct cfq_data, unplug_work); 3807 struct request_queue *q = cfqd->queue; 3808 3809 spin_lock_irq(q->queue_lock); 3810 __blk_run_queue(cfqd->queue); 3811 spin_unlock_irq(q->queue_lock); 3812} 3813 3814/* 3815 * Timer running if the active_queue is currently idling inside its time slice 3816 */ 3817static void cfq_idle_slice_timer(unsigned long data) 3818{ 3819 struct cfq_data *cfqd = (struct cfq_data *) data; 3820 struct cfq_queue *cfqq; 3821 unsigned long flags; 3822 int timed_out = 1; 3823 3824 cfq_log(cfqd, "idle timer fired"); 3825 3826 spin_lock_irqsave(cfqd->queue->queue_lock, flags); 3827 3828 cfqq = cfqd->active_queue; 3829 if (cfqq) { 3830 timed_out = 0; 3831 3832 /* 3833 * We saw a request before the queue expired, let it through 3834 */ 3835 if (cfq_cfqq_must_dispatch(cfqq)) 3836 goto out_kick; 3837 3838 /* 3839 * expired 3840 */ 3841 if (cfq_slice_used(cfqq)) 3842 goto expire; 3843 3844 /* 3845 * only expire and reinvoke request handler, if there are 3846 * other queues with pending requests 3847 */ 3848 if (!cfqd->busy_queues) 3849 goto out_cont; 3850 3851 /* 3852 * not expired and it has a request pending, let it dispatch 3853 */ 3854 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) 3855 goto out_kick; 3856 3857 /* 3858 * Queue depth flag is reset only when the idle didn't succeed 3859 */ 3860 cfq_clear_cfqq_deep(cfqq); 3861 } 3862expire: 3863 cfq_slice_expired(cfqd, timed_out); 3864out_kick: 3865 cfq_schedule_dispatch(cfqd); 3866out_cont: 3867 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); 3868} 3869 3870static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) 3871{ 3872 del_timer_sync(&cfqd->idle_slice_timer); 3873 cancel_work_sync(&cfqd->unplug_work); 3874} 3875 3876static void cfq_put_async_queues(struct cfq_data *cfqd) 3877{ 3878 int i; 3879 3880 for (i = 0; i < IOPRIO_BE_NR; i++) { 3881 if (cfqd->async_cfqq[0][i]) 3882 cfq_put_queue(cfqd->async_cfqq[0][i]); 3883 if (cfqd->async_cfqq[1][i]) 3884 cfq_put_queue(cfqd->async_cfqq[1][i]); 3885 } 3886 3887 if (cfqd->async_idle_cfqq) 3888 cfq_put_queue(cfqd->async_idle_cfqq); 3889} 3890 3891static void cfq_exit_queue(struct elevator_queue *e) 3892{ 3893 struct cfq_data *cfqd = e->elevator_data; 3894 struct request_queue *q = cfqd->queue; 3895 bool wait = false; 3896 3897 cfq_shutdown_timer_wq(cfqd); 3898 3899 spin_lock_irq(q->queue_lock); 3900 3901 if (cfqd->active_queue) 3902 __cfq_slice_expired(cfqd, cfqd->active_queue, 0); 3903 3904 while (!list_empty(&cfqd->cic_list)) { 3905 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, 3906 struct cfq_io_context, 3907 queue_list); 3908 3909 __cfq_exit_single_io_context(cfqd, cic); 3910 } 3911 3912 cfq_put_async_queues(cfqd); 3913 cfq_release_cfq_groups(cfqd); 3914 3915 /* 3916 * If there are groups which we could not unlink from blkcg list, 3917 * wait for a rcu period for them to be freed. 3918 */ 3919 if (cfqd->nr_blkcg_linked_grps) 3920 wait = true; 3921 3922 spin_unlock_irq(q->queue_lock); 3923 3924 cfq_shutdown_timer_wq(cfqd); 3925 3926 spin_lock(&cic_index_lock); 3927 ida_remove(&cic_index_ida, cfqd->cic_index); 3928 spin_unlock(&cic_index_lock); 3929 3930 /* 3931 * Wait for cfqg->blkg->key accessors to exit their grace periods. 3932 * Do this wait only if there are other unlinked groups out 3933 * there. This can happen if cgroup deletion path claimed the 3934 * responsibility of cleaning up a group before queue cleanup code 3935 * get to the group. 3936 * 3937 * Do not call synchronize_rcu() unconditionally as there are drivers 3938 * which create/delete request queue hundreds of times during scan/boot 3939 * and synchronize_rcu() can take significant time and slow down boot. 3940 */ 3941 if (wait) 3942 synchronize_rcu(); 3943 kfree(cfqd); 3944} 3945 3946static int cfq_alloc_cic_index(void) 3947{ 3948 int index, error; 3949 3950 do { 3951 if (!ida_pre_get(&cic_index_ida, GFP_KERNEL)) 3952 return -ENOMEM; 3953 3954 spin_lock(&cic_index_lock); 3955 error = ida_get_new(&cic_index_ida, &index); 3956 spin_unlock(&cic_index_lock); 3957 if (error && error != -EAGAIN) 3958 return error; 3959 } while (error); 3960 3961 return index; 3962} 3963 3964static void *cfq_init_queue(struct request_queue *q) 3965{ 3966 struct cfq_data *cfqd; 3967 int i, j; 3968 struct cfq_group *cfqg; 3969 struct cfq_rb_root *st; 3970 3971 i = cfq_alloc_cic_index(); 3972 if (i < 0) 3973 return NULL; 3974 3975 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); 3976 if (!cfqd) 3977 return NULL; 3978 3979 /* 3980 * Don't need take queue_lock in the routine, since we are 3981 * initializing the ioscheduler, and nobody is using cfqd 3982 */ 3983 cfqd->cic_index = i; 3984 3985 /* Init root service tree */ 3986 cfqd->grp_service_tree = CFQ_RB_ROOT; 3987 3988 /* Init root group */ 3989 cfqg = &cfqd->root_group; 3990 for_each_cfqg_st(cfqg, i, j, st) 3991 *st = CFQ_RB_ROOT; 3992 RB_CLEAR_NODE(&cfqg->rb_node); 3993 3994 /* Give preference to root group over other groups */ 3995 cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT; 3996 3997#ifdef CONFIG_CFQ_GROUP_IOSCHED 3998 /* 3999 * Set root group reference to 2. One reference will be dropped when 4000 * all groups on cfqd->cfqg_list are being deleted during queue exit. 4001 * Other reference will remain there as we don't want to delete this 4002 * group as it is statically allocated and gets destroyed when 4003 * throtl_data goes away. 4004 */ 4005 cfqg->ref = 2; 4006 4007 if (blkio_alloc_blkg_stats(&cfqg->blkg)) { 4008 kfree(cfqg); 4009 kfree(cfqd); 4010 return NULL; 4011 } 4012 4013 rcu_read_lock(); 4014 4015 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg, 4016 (void *)cfqd, 0); 4017 rcu_read_unlock(); 4018 cfqd->nr_blkcg_linked_grps++; 4019 4020 /* Add group on cfqd->cfqg_list */ 4021 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list); 4022#endif 4023 /* 4024 * Not strictly needed (since RB_ROOT just clears the node and we 4025 * zeroed cfqd on alloc), but better be safe in case someone decides 4026 * to add magic to the rb code 4027 */ 4028 for (i = 0; i < CFQ_PRIO_LISTS; i++) 4029 cfqd->prio_trees[i] = RB_ROOT; 4030 4031 /* 4032 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues. 4033 * Grab a permanent reference to it, so that the normal code flow 4034 * will not attempt to free it. 4035 */ 4036 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0); 4037 cfqd->oom_cfqq.ref++; 4038 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group); 4039 4040 INIT_LIST_HEAD(&cfqd->cic_list); 4041 4042 cfqd->queue = q; 4043 4044 init_timer(&cfqd->idle_slice_timer); 4045 cfqd->idle_slice_timer.function = cfq_idle_slice_timer; 4046 cfqd->idle_slice_timer.data = (unsigned long) cfqd; 4047 4048 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); 4049 4050 cfqd->cfq_quantum = cfq_quantum; 4051 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; 4052 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; 4053 cfqd->cfq_back_max = cfq_back_max; 4054 cfqd->cfq_back_penalty = cfq_back_penalty; 4055 cfqd->cfq_slice[0] = cfq_slice_async; 4056 cfqd->cfq_slice[1] = cfq_slice_sync; 4057 cfqd->cfq_slice_async_rq = cfq_slice_async_rq; 4058 cfqd->cfq_slice_idle = cfq_slice_idle; 4059 cfqd->cfq_group_idle = cfq_group_idle; 4060 cfqd->cfq_latency = 1; 4061 cfqd->hw_tag = -1; 4062 /* 4063 * we optimistically start assuming sync ops weren't delayed in last 4064 * second, in order to have larger depth for async operations. 4065 */ 4066 cfqd->last_delayed_sync = jiffies - HZ; 4067 return cfqd; 4068} 4069 4070static void cfq_slab_kill(void) 4071{ 4072 /* 4073 * Caller already ensured that pending RCU callbacks are completed, 4074 * so we should have no busy allocations at this point. 4075 */ 4076 if (cfq_pool) 4077 kmem_cache_destroy(cfq_pool); 4078 if (cfq_ioc_pool) 4079 kmem_cache_destroy(cfq_ioc_pool); 4080} 4081 4082static int __init cfq_slab_setup(void) 4083{ 4084 cfq_pool = KMEM_CACHE(cfq_queue, 0); 4085 if (!cfq_pool) 4086 goto fail; 4087 4088 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0); 4089 if (!cfq_ioc_pool) 4090 goto fail; 4091 4092 return 0; 4093fail: 4094 cfq_slab_kill(); 4095 return -ENOMEM; 4096} 4097 4098/* 4099 * sysfs parts below --> 4100 */ 4101static ssize_t 4102cfq_var_show(unsigned int var, char *page) 4103{ 4104 return sprintf(page, "%d\n", var); 4105} 4106 4107static ssize_t 4108cfq_var_store(unsigned int *var, const char *page, size_t count) 4109{ 4110 char *p = (char *) page; 4111 4112 *var = simple_strtoul(p, &p, 10); 4113 return count; 4114} 4115 4116#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ 4117static ssize_t __FUNC(struct elevator_queue *e, char *page) \ 4118{ \ 4119 struct cfq_data *cfqd = e->elevator_data; \ 4120 unsigned int __data = __VAR; \ 4121 if (__CONV) \ 4122 __data = jiffies_to_msecs(__data); \ 4123 return cfq_var_show(__data, (page)); \ 4124} 4125SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); 4126SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); 4127SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); 4128SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); 4129SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); 4130SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); 4131SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1); 4132SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); 4133SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); 4134SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); 4135SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0); 4136#undef SHOW_FUNCTION 4137 4138#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ 4139static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \ 4140{ \ 4141 struct cfq_data *cfqd = e->elevator_data; \ 4142 unsigned int __data; \ 4143 int ret = cfq_var_store(&__data, (page), count); \ 4144 if (__data < (MIN)) \ 4145 __data = (MIN); \ 4146 else if (__data > (MAX)) \ 4147 __data = (MAX); \ 4148 if (__CONV) \ 4149 *(__PTR) = msecs_to_jiffies(__data); \ 4150 else \ 4151 *(__PTR) = __data; \ 4152 return ret; \ 4153} 4154STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); 4155STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, 4156 UINT_MAX, 1); 4157STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, 4158 UINT_MAX, 1); 4159STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); 4160STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, 4161 UINT_MAX, 0); 4162STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); 4163STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1); 4164STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); 4165STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); 4166STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, 4167 UINT_MAX, 0); 4168STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0); 4169#undef STORE_FUNCTION 4170 4171#define CFQ_ATTR(name) \ 4172 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) 4173 4174static struct elv_fs_entry cfq_attrs[] = { 4175 CFQ_ATTR(quantum), 4176 CFQ_ATTR(fifo_expire_sync), 4177 CFQ_ATTR(fifo_expire_async), 4178 CFQ_ATTR(back_seek_max), 4179 CFQ_ATTR(back_seek_penalty), 4180 CFQ_ATTR(slice_sync), 4181 CFQ_ATTR(slice_async), 4182 CFQ_ATTR(slice_async_rq), 4183 CFQ_ATTR(slice_idle), 4184 CFQ_ATTR(group_idle), 4185 CFQ_ATTR(low_latency), 4186 __ATTR_NULL 4187}; 4188 4189static struct elevator_type iosched_cfq = { 4190 .ops = { 4191 .elevator_merge_fn = cfq_merge, 4192 .elevator_merged_fn = cfq_merged_request, 4193 .elevator_merge_req_fn = cfq_merged_requests, 4194 .elevator_allow_merge_fn = cfq_allow_merge, 4195 .elevator_bio_merged_fn = cfq_bio_merged, 4196 .elevator_dispatch_fn = cfq_dispatch_requests, 4197 .elevator_add_req_fn = cfq_insert_request, 4198 .elevator_activate_req_fn = cfq_activate_request, 4199 .elevator_deactivate_req_fn = cfq_deactivate_request, 4200 .elevator_completed_req_fn = cfq_completed_request, 4201 .elevator_former_req_fn = elv_rb_former_request, 4202 .elevator_latter_req_fn = elv_rb_latter_request, 4203 .elevator_set_req_fn = cfq_set_request, 4204 .elevator_put_req_fn = cfq_put_request, 4205 .elevator_may_queue_fn = cfq_may_queue, 4206 .elevator_init_fn = cfq_init_queue, 4207 .elevator_exit_fn = cfq_exit_queue, 4208 .trim = cfq_free_io_context, 4209 }, 4210 .elevator_attrs = cfq_attrs, 4211 .elevator_name = "cfq", 4212 .elevator_owner = THIS_MODULE, 4213}; 4214 4215#ifdef CONFIG_CFQ_GROUP_IOSCHED 4216static struct blkio_policy_type blkio_policy_cfq = { 4217 .ops = { 4218 .blkio_unlink_group_fn = cfq_unlink_blkio_group, 4219 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight, 4220 }, 4221 .plid = BLKIO_POLICY_PROP, 4222}; 4223#else 4224static struct blkio_policy_type blkio_policy_cfq; 4225#endif 4226 4227static int __init cfq_init(void) 4228{ 4229 /* 4230 * could be 0 on HZ < 1000 setups 4231 */ 4232 if (!cfq_slice_async) 4233 cfq_slice_async = 1; 4234 if (!cfq_slice_idle) 4235 cfq_slice_idle = 1; 4236 4237#ifdef CONFIG_CFQ_GROUP_IOSCHED 4238 if (!cfq_group_idle) 4239 cfq_group_idle = 1; 4240#else 4241 cfq_group_idle = 0; 4242#endif 4243 if (cfq_slab_setup()) 4244 return -ENOMEM; 4245 4246 elv_register(&iosched_cfq); 4247 blkio_policy_register(&blkio_policy_cfq); 4248 4249 return 0; 4250} 4251 4252static void __exit cfq_exit(void) 4253{ 4254 DECLARE_COMPLETION_ONSTACK(all_gone); 4255 blkio_policy_unregister(&blkio_policy_cfq); 4256 elv_unregister(&iosched_cfq); 4257 ioc_gone = &all_gone; 4258 /* ioc_gone's update must be visible before reading ioc_count */ 4259 smp_wmb(); 4260 4261 /* 4262 * this also protects us from entering cfq_slab_kill() with 4263 * pending RCU callbacks 4264 */ 4265 if (elv_ioc_count_read(cfq_ioc_count)) 4266 wait_for_completion(&all_gone); 4267 ida_destroy(&cic_index_ida); 4268 cfq_slab_kill(); 4269} 4270 4271module_init(cfq_init); 4272module_exit(cfq_exit); 4273 4274MODULE_AUTHOR("Jens Axboe"); 4275MODULE_LICENSE("GPL"); 4276MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); 4277