1/* SPDX-License-Identifier: GPL-2.0-or-later */ 2/* 3 * Header file for the BFQ I/O scheduler: data structures and 4 * prototypes of interface functions among BFQ components. 5 */ 6#ifndef _BFQ_H 7#define _BFQ_H 8 9#include <linux/blktrace_api.h> 10#include <linux/hrtimer.h> 11 12#include "blk-cgroup-rwstat.h" 13 14#define BFQ_IOPRIO_CLASSES 3 15#define BFQ_CL_IDLE_TIMEOUT (HZ/5) 16 17#define BFQ_MIN_WEIGHT 1 18#define BFQ_MAX_WEIGHT 1000 19#define BFQ_WEIGHT_CONVERSION_COEFF 10 20 21#define BFQ_DEFAULT_QUEUE_IOPRIO 4 22 23#define BFQ_DEFAULT_GRP_IOPRIO 0 24#define BFQ_DEFAULT_GRP_CLASS IOPRIO_CLASS_BE 25 26#define MAX_BFQQ_NAME_LENGTH 16 27 28/* 29 * Soft real-time applications are extremely more latency sensitive 30 * than interactive ones. Over-raise the weight of the former to 31 * privilege them against the latter. 32 */ 33#define BFQ_SOFTRT_WEIGHT_FACTOR 100 34 35/* 36 * Maximum number of actuators supported. This constant is used simply 37 * to define the size of the static array that will contain 38 * per-actuator data. The current value is hopefully a good upper 39 * bound to the possible number of actuators of any actual drive. 40 */ 41#define BFQ_MAX_ACTUATORS 8 42 43struct bfq_entity; 44 45/** 46 * struct bfq_service_tree - per ioprio_class service tree. 47 * 48 * Each service tree represents a B-WF2Q+ scheduler on its own. Each 49 * ioprio_class has its own independent scheduler, and so its own 50 * bfq_service_tree. All the fields are protected by the queue lock 51 * of the containing bfqd. 52 */ 53struct bfq_service_tree { 54 /* tree for active entities (i.e., those backlogged) */ 55 struct rb_root active; 56 /* tree for idle entities (i.e., not backlogged, with V < F_i)*/ 57 struct rb_root idle; 58 59 /* idle entity with minimum F_i */ 60 struct bfq_entity *first_idle; 61 /* idle entity with maximum F_i */ 62 struct bfq_entity *last_idle; 63 64 /* scheduler virtual time */ 65 u64 vtime; 66 /* scheduler weight sum; active and idle entities contribute to it */ 67 unsigned long wsum; 68}; 69 70/** 71 * struct bfq_sched_data - multi-class scheduler. 72 * 73 * bfq_sched_data is the basic scheduler queue. It supports three 74 * ioprio_classes, and can be used either as a toplevel queue or as an 75 * intermediate queue in a hierarchical setup. 76 * 77 * The supported ioprio_classes are the same as in CFQ, in descending 78 * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE. 79 * Requests from higher priority queues are served before all the 80 * requests from lower priority queues; among requests of the same 81 * queue requests are served according to B-WF2Q+. 82 * 83 * The schedule is implemented by the service trees, plus the field 84 * @next_in_service, which points to the entity on the active trees 85 * that will be served next, if 1) no changes in the schedule occurs 86 * before the current in-service entity is expired, 2) the in-service 87 * queue becomes idle when it expires, and 3) if the entity pointed by 88 * in_service_entity is not a queue, then the in-service child entity 89 * of the entity pointed by in_service_entity becomes idle on 90 * expiration. This peculiar definition allows for the following 91 * optimization, not yet exploited: while a given entity is still in 92 * service, we already know which is the best candidate for next 93 * service among the other active entities in the same parent 94 * entity. We can then quickly compare the timestamps of the 95 * in-service entity with those of such best candidate. 96 * 97 * All fields are protected by the lock of the containing bfqd. 98 */ 99struct bfq_sched_data { 100 /* entity in service */ 101 struct bfq_entity *in_service_entity; 102 /* head-of-line entity (see comments above) */ 103 struct bfq_entity *next_in_service; 104 /* array of service trees, one per ioprio_class */ 105 struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES]; 106 /* last time CLASS_IDLE was served */ 107 unsigned long bfq_class_idle_last_service; 108 109}; 110 111/** 112 * struct bfq_weight_counter - counter of the number of all active queues 113 * with a given weight. 114 */ 115struct bfq_weight_counter { 116 unsigned int weight; /* weight of the queues this counter refers to */ 117 unsigned int num_active; /* nr of active queues with this weight */ 118 /* 119 * Weights tree member (see bfq_data's @queue_weights_tree) 120 */ 121 struct rb_node weights_node; 122}; 123 124/** 125 * struct bfq_entity - schedulable entity. 126 * 127 * A bfq_entity is used to represent either a bfq_queue (leaf node in the 128 * cgroup hierarchy) or a bfq_group into the upper level scheduler. Each 129 * entity belongs to the sched_data of the parent group in the cgroup 130 * hierarchy. Non-leaf entities have also their own sched_data, stored 131 * in @my_sched_data. 132 * 133 * Each entity stores independently its priority values; this would 134 * allow different weights on different devices, but this 135 * functionality is not exported to userspace by now. Priorities and 136 * weights are updated lazily, first storing the new values into the 137 * new_* fields, then setting the @prio_changed flag. As soon as 138 * there is a transition in the entity state that allows the priority 139 * update to take place the effective and the requested priority 140 * values are synchronized. 141 * 142 * Unless cgroups are used, the weight value is calculated from the 143 * ioprio to export the same interface as CFQ. When dealing with 144 * "well-behaved" queues (i.e., queues that do not spend too much 145 * time to consume their budget and have true sequential behavior, and 146 * when there are no external factors breaking anticipation) the 147 * relative weights at each level of the cgroups hierarchy should be 148 * guaranteed. All the fields are protected by the queue lock of the 149 * containing bfqd. 150 */ 151struct bfq_entity { 152 /* service_tree member */ 153 struct rb_node rb_node; 154 155 /* 156 * Flag, true if the entity is on a tree (either the active or 157 * the idle one of its service_tree) or is in service. 158 */ 159 bool on_st_or_in_serv; 160 161 /* B-WF2Q+ start and finish timestamps [sectors/weight] */ 162 u64 start, finish; 163 164 /* tree the entity is enqueued into; %NULL if not on a tree */ 165 struct rb_root *tree; 166 167 /* 168 * minimum start time of the (active) subtree rooted at this 169 * entity; used for O(log N) lookups into active trees 170 */ 171 u64 min_start; 172 173 /* amount of service received during the last service slot */ 174 int service; 175 176 /* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */ 177 int budget; 178 179 /* Number of requests allocated in the subtree of this entity */ 180 int allocated; 181 182 /* device weight, if non-zero, it overrides the default weight of 183 * bfq_group_data */ 184 int dev_weight; 185 /* weight of the queue */ 186 int weight; 187 /* next weight if a change is in progress */ 188 int new_weight; 189 190 /* original weight, used to implement weight boosting */ 191 int orig_weight; 192 193 /* parent entity, for hierarchical scheduling */ 194 struct bfq_entity *parent; 195 196 /* 197 * For non-leaf nodes in the hierarchy, the associated 198 * scheduler queue, %NULL on leaf nodes. 199 */ 200 struct bfq_sched_data *my_sched_data; 201 /* the scheduler queue this entity belongs to */ 202 struct bfq_sched_data *sched_data; 203 204 /* flag, set to request a weight, ioprio or ioprio_class change */ 205 int prio_changed; 206 207#ifdef CONFIG_BFQ_GROUP_IOSCHED 208 /* flag, set if the entity is counted in groups_with_pending_reqs */ 209 bool in_groups_with_pending_reqs; 210#endif 211 212 /* last child queue of entity created (for non-leaf entities) */ 213 struct bfq_queue *last_bfqq_created; 214}; 215 216struct bfq_group; 217 218/** 219 * struct bfq_ttime - per process thinktime stats. 220 */ 221struct bfq_ttime { 222 /* completion time of the last request */ 223 u64 last_end_request; 224 225 /* total process thinktime */ 226 u64 ttime_total; 227 /* number of thinktime samples */ 228 unsigned long ttime_samples; 229 /* average process thinktime */ 230 u64 ttime_mean; 231}; 232 233/** 234 * struct bfq_queue - leaf schedulable entity. 235 * 236 * A bfq_queue is a leaf request queue; it can be associated with an 237 * io_context or more, if it is async or shared between cooperating 238 * processes. Besides, it contains I/O requests for only one actuator 239 * (an io_context is associated with a different bfq_queue for each 240 * actuator it generates I/O for). @cgroup holds a reference to the 241 * cgroup, to be sure that it does not disappear while a bfqq still 242 * references it (mostly to avoid races between request issuing and 243 * task migration followed by cgroup destruction). All the fields are 244 * protected by the queue lock of the containing bfqd. 245 */ 246struct bfq_queue { 247 /* reference counter */ 248 int ref; 249 /* counter of references from other queues for delayed stable merge */ 250 int stable_ref; 251 /* parent bfq_data */ 252 struct bfq_data *bfqd; 253 254 /* current ioprio and ioprio class */ 255 unsigned short ioprio, ioprio_class; 256 /* next ioprio and ioprio class if a change is in progress */ 257 unsigned short new_ioprio, new_ioprio_class; 258 259 /* last total-service-time sample, see bfq_update_inject_limit() */ 260 u64 last_serv_time_ns; 261 /* limit for request injection */ 262 unsigned int inject_limit; 263 /* last time the inject limit has been decreased, in jiffies */ 264 unsigned long decrease_time_jif; 265 266 /* 267 * Shared bfq_queue if queue is cooperating with one or more 268 * other queues. 269 */ 270 struct bfq_queue *new_bfqq; 271 /* request-position tree member (see bfq_group's @rq_pos_tree) */ 272 struct rb_node pos_node; 273 /* request-position tree root (see bfq_group's @rq_pos_tree) */ 274 struct rb_root *pos_root; 275 276 /* sorted list of pending requests */ 277 struct rb_root sort_list; 278 /* if fifo isn't expired, next request to serve */ 279 struct request *next_rq; 280 /* number of sync and async requests queued */ 281 int queued[2]; 282 /* number of pending metadata requests */ 283 int meta_pending; 284 /* fifo list of requests in sort_list */ 285 struct list_head fifo; 286 287 /* entity representing this queue in the scheduler */ 288 struct bfq_entity entity; 289 290 /* pointer to the weight counter associated with this entity */ 291 struct bfq_weight_counter *weight_counter; 292 293 /* maximum budget allowed from the feedback mechanism */ 294 int max_budget; 295 /* budget expiration (in jiffies) */ 296 unsigned long budget_timeout; 297 298 /* number of requests on the dispatch list or inside driver */ 299 int dispatched; 300 301 /* status flags */ 302 unsigned long flags; 303 304 /* node for active/idle bfqq list inside parent bfqd */ 305 struct list_head bfqq_list; 306 307 /* associated @bfq_ttime struct */ 308 struct bfq_ttime ttime; 309 310 /* when bfqq started to do I/O within the last observation window */ 311 u64 io_start_time; 312 /* how long bfqq has remained empty during the last observ. window */ 313 u64 tot_idle_time; 314 315 /* bit vector: a 1 for each seeky requests in history */ 316 u32 seek_history; 317 318 /* node for the device's burst list */ 319 struct hlist_node burst_list_node; 320 321 /* position of the last request enqueued */ 322 sector_t last_request_pos; 323 324 /* Number of consecutive pairs of request completion and 325 * arrival, such that the queue becomes idle after the 326 * completion, but the next request arrives within an idle 327 * time slice; used only if the queue's IO_bound flag has been 328 * cleared. 329 */ 330 unsigned int requests_within_timer; 331 332 /* pid of the process owning the queue, used for logging purposes */ 333 pid_t pid; 334 335 /* 336 * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL 337 * if the queue is shared. 338 */ 339 struct bfq_io_cq *bic; 340 341 /* current maximum weight-raising time for this queue */ 342 unsigned long wr_cur_max_time; 343 /* 344 * Minimum time instant such that, only if a new request is 345 * enqueued after this time instant in an idle @bfq_queue with 346 * no outstanding requests, then the task associated with the 347 * queue it is deemed as soft real-time (see the comments on 348 * the function bfq_bfqq_softrt_next_start()) 349 */ 350 unsigned long soft_rt_next_start; 351 /* 352 * Start time of the current weight-raising period if 353 * the @bfq-queue is being weight-raised, otherwise 354 * finish time of the last weight-raising period. 355 */ 356 unsigned long last_wr_start_finish; 357 /* factor by which the weight of this queue is multiplied */ 358 unsigned int wr_coeff; 359 /* 360 * Time of the last transition of the @bfq_queue from idle to 361 * backlogged. 362 */ 363 unsigned long last_idle_bklogged; 364 /* 365 * Cumulative service received from the @bfq_queue since the 366 * last transition from idle to backlogged. 367 */ 368 unsigned long service_from_backlogged; 369 /* 370 * Cumulative service received from the @bfq_queue since its 371 * last transition to weight-raised state. 372 */ 373 unsigned long service_from_wr; 374 375 /* 376 * Value of wr start time when switching to soft rt 377 */ 378 unsigned long wr_start_at_switch_to_srt; 379 380 unsigned long split_time; /* time of last split */ 381 382 unsigned long first_IO_time; /* time of first I/O for this queue */ 383 unsigned long creation_time; /* when this queue is created */ 384 385 /* 386 * Pointer to the waker queue for this queue, i.e., to the 387 * queue Q such that this queue happens to get new I/O right 388 * after some I/O request of Q is completed. For details, see 389 * the comments on the choice of the queue for injection in 390 * bfq_select_queue(). 391 */ 392 struct bfq_queue *waker_bfqq; 393 /* pointer to the curr. tentative waker queue, see bfq_check_waker() */ 394 struct bfq_queue *tentative_waker_bfqq; 395 /* number of times the same tentative waker has been detected */ 396 unsigned int num_waker_detections; 397 /* time when we started considering this waker */ 398 u64 waker_detection_started; 399 400 /* node for woken_list, see below */ 401 struct hlist_node woken_list_node; 402 /* 403 * Head of the list of the woken queues for this queue, i.e., 404 * of the list of the queues for which this queue is a waker 405 * queue. This list is used to reset the waker_bfqq pointer in 406 * the woken queues when this queue exits. 407 */ 408 struct hlist_head woken_list; 409 410 /* index of the actuator this queue is associated with */ 411 unsigned int actuator_idx; 412}; 413 414/** 415* struct bfq_data - bfqq data unique and persistent for associated bfq_io_cq 416*/ 417struct bfq_iocq_bfqq_data { 418 /* 419 * Snapshot of the has_short_time flag before merging; taken 420 * to remember its values while the queue is merged, so as to 421 * be able to restore it in case of split. 422 */ 423 bool saved_has_short_ttime; 424 /* 425 * Same purpose as the previous two fields for the I/O bound 426 * classification of a queue. 427 */ 428 bool saved_IO_bound; 429 430 u64 saved_io_start_time; 431 u64 saved_tot_idle_time; 432 433 /* 434 * Same purpose as the previous fields for the values of the 435 * field keeping the queue's belonging to a large burst 436 */ 437 bool saved_in_large_burst; 438 /* 439 * True if the queue belonged to a burst list before its merge 440 * with another cooperating queue. 441 */ 442 bool was_in_burst_list; 443 444 /* 445 * Save the weight when a merge occurs, to be able 446 * to restore it in case of split. If the weight is not 447 * correctly resumed when the queue is recycled, 448 * then the weight of the recycled queue could differ 449 * from the weight of the original queue. 450 */ 451 unsigned int saved_weight; 452 453 /* 454 * Similar to previous fields: save wr information. 455 */ 456 unsigned long saved_wr_coeff; 457 unsigned long saved_last_wr_start_finish; 458 unsigned long saved_service_from_wr; 459 unsigned long saved_wr_start_at_switch_to_srt; 460 unsigned int saved_wr_cur_max_time; 461 struct bfq_ttime saved_ttime; 462 463 /* Save also injection state */ 464 u64 saved_last_serv_time_ns; 465 unsigned int saved_inject_limit; 466 unsigned long saved_decrease_time_jif; 467 468 /* candidate queue for a stable merge (due to close creation time) */ 469 struct bfq_queue *stable_merge_bfqq; 470 471 bool stably_merged; /* non splittable if true */ 472}; 473 474/** 475 * struct bfq_io_cq - per (request_queue, io_context) structure. 476 */ 477struct bfq_io_cq { 478 /* associated io_cq structure */ 479 struct io_cq icq; /* must be the first member */ 480 /* 481 * Matrix of associated process queues: first row for async 482 * queues, second row sync queues. Each row contains one 483 * column for each actuator. An I/O request generated by the 484 * process is inserted into the queue pointed by bfqq[i][j] if 485 * the request is to be served by the j-th actuator of the 486 * drive, where i==0 or i==1, depending on whether the request 487 * is async or sync. So there is a distinct queue for each 488 * actuator. 489 */ 490 struct bfq_queue *bfqq[2][BFQ_MAX_ACTUATORS]; 491 /* per (request_queue, blkcg) ioprio */ 492 int ioprio; 493#ifdef CONFIG_BFQ_GROUP_IOSCHED 494 uint64_t blkcg_serial_nr; /* the current blkcg serial */ 495#endif 496 497 /* 498 * Persistent data for associated synchronous process queues 499 * (one queue per actuator, see field bfqq above). In 500 * particular, each of these queues may undergo a merge. 501 */ 502 struct bfq_iocq_bfqq_data bfqq_data[BFQ_MAX_ACTUATORS]; 503 504 unsigned int requests; /* Number of requests this process has in flight */ 505}; 506 507/** 508 * struct bfq_data - per-device data structure. 509 * 510 * All the fields are protected by @lock. 511 */ 512struct bfq_data { 513 /* device request queue */ 514 struct request_queue *queue; 515 /* dispatch queue */ 516 struct list_head dispatch; 517 518 /* root bfq_group for the device */ 519 struct bfq_group *root_group; 520 521 /* 522 * rbtree of weight counters of @bfq_queues, sorted by 523 * weight. Used to keep track of whether all @bfq_queues have 524 * the same weight. The tree contains one counter for each 525 * distinct weight associated to some active and not 526 * weight-raised @bfq_queue (see the comments to the functions 527 * bfq_weights_tree_[add|remove] for further details). 528 */ 529 struct rb_root_cached queue_weights_tree; 530 531#ifdef CONFIG_BFQ_GROUP_IOSCHED 532 /* 533 * Number of groups with at least one process that 534 * has at least one request waiting for completion. Note that 535 * this accounts for also requests already dispatched, but not 536 * yet completed. Therefore this number of groups may differ 537 * (be larger) than the number of active groups, as a group is 538 * considered active only if its corresponding entity has 539 * queues with at least one request queued. This 540 * number is used to decide whether a scenario is symmetric. 541 * For a detailed explanation see comments on the computation 542 * of the variable asymmetric_scenario in the function 543 * bfq_better_to_idle(). 544 * 545 * However, it is hard to compute this number exactly, for 546 * groups with multiple processes. Consider a group 547 * that is inactive, i.e., that has no process with 548 * pending I/O inside BFQ queues. Then suppose that 549 * num_groups_with_pending_reqs is still accounting for this 550 * group, because the group has processes with some 551 * I/O request still in flight. num_groups_with_pending_reqs 552 * should be decremented when the in-flight request of the 553 * last process is finally completed (assuming that 554 * nothing else has changed for the group in the meantime, in 555 * terms of composition of the group and active/inactive state of child 556 * groups and processes). To accomplish this, an additional 557 * pending-request counter must be added to entities, and must 558 * be updated correctly. To avoid this additional field and operations, 559 * we resort to the following tradeoff between simplicity and 560 * accuracy: for an inactive group that is still counted in 561 * num_groups_with_pending_reqs, we decrement 562 * num_groups_with_pending_reqs when the first 563 * process of the group remains with no request waiting for 564 * completion. 565 * 566 * Even this simpler decrement strategy requires a little 567 * carefulness: to avoid multiple decrements, we flag a group, 568 * more precisely an entity representing a group, as still 569 * counted in num_groups_with_pending_reqs when it becomes 570 * inactive. Then, when the first queue of the 571 * entity remains with no request waiting for completion, 572 * num_groups_with_pending_reqs is decremented, and this flag 573 * is reset. After this flag is reset for the entity, 574 * num_groups_with_pending_reqs won't be decremented any 575 * longer in case a new queue of the entity remains 576 * with no request waiting for completion. 577 */ 578 unsigned int num_groups_with_pending_reqs; 579#endif 580 581 /* 582 * Per-class (RT, BE, IDLE) number of bfq_queues containing 583 * requests (including the queue in service, even if it is 584 * idling). 585 */ 586 unsigned int busy_queues[3]; 587 /* number of weight-raised busy @bfq_queues */ 588 int wr_busy_queues; 589 /* number of queued requests */ 590 int queued; 591 /* number of requests dispatched and waiting for completion */ 592 int tot_rq_in_driver; 593 /* 594 * number of requests dispatched and waiting for completion 595 * for each actuator 596 */ 597 int rq_in_driver[BFQ_MAX_ACTUATORS]; 598 599 /* true if the device is non rotational and performs queueing */ 600 bool nonrot_with_queueing; 601 602 /* 603 * Maximum number of requests in driver in the last 604 * @hw_tag_samples completed requests. 605 */ 606 int max_rq_in_driver; 607 /* number of samples used to calculate hw_tag */ 608 int hw_tag_samples; 609 /* flag set to one if the driver is showing a queueing behavior */ 610 int hw_tag; 611 612 /* number of budgets assigned */ 613 int budgets_assigned; 614 615 /* 616 * Timer set when idling (waiting) for the next request from 617 * the queue in service. 618 */ 619 struct hrtimer idle_slice_timer; 620 621 /* bfq_queue in service */ 622 struct bfq_queue *in_service_queue; 623 624 /* on-disk position of the last served request */ 625 sector_t last_position; 626 627 /* position of the last served request for the in-service queue */ 628 sector_t in_serv_last_pos; 629 630 /* time of last request completion (ns) */ 631 u64 last_completion; 632 633 /* bfqq owning the last completed rq */ 634 struct bfq_queue *last_completed_rq_bfqq; 635 636 /* last bfqq created, among those in the root group */ 637 struct bfq_queue *last_bfqq_created; 638 639 /* time of last transition from empty to non-empty (ns) */ 640 u64 last_empty_occupied_ns; 641 642 /* 643 * Flag set to activate the sampling of the total service time 644 * of a just-arrived first I/O request (see 645 * bfq_update_inject_limit()). This will cause the setting of 646 * waited_rq when the request is finally dispatched. 647 */ 648 bool wait_dispatch; 649 /* 650 * If set, then bfq_update_inject_limit() is invoked when 651 * waited_rq is eventually completed. 652 */ 653 struct request *waited_rq; 654 /* 655 * True if some request has been injected during the last service hole. 656 */ 657 bool rqs_injected; 658 659 /* time of first rq dispatch in current observation interval (ns) */ 660 u64 first_dispatch; 661 /* time of last rq dispatch in current observation interval (ns) */ 662 u64 last_dispatch; 663 664 /* beginning of the last budget */ 665 ktime_t last_budget_start; 666 /* beginning of the last idle slice */ 667 ktime_t last_idling_start; 668 unsigned long last_idling_start_jiffies; 669 670 /* number of samples in current observation interval */ 671 int peak_rate_samples; 672 /* num of samples of seq dispatches in current observation interval */ 673 u32 sequential_samples; 674 /* total num of sectors transferred in current observation interval */ 675 u64 tot_sectors_dispatched; 676 /* max rq size seen during current observation interval (sectors) */ 677 u32 last_rq_max_size; 678 /* time elapsed from first dispatch in current observ. interval (us) */ 679 u64 delta_from_first; 680 /* 681 * Current estimate of the device peak rate, measured in 682 * [(sectors/usec) / 2^BFQ_RATE_SHIFT]. The left-shift by 683 * BFQ_RATE_SHIFT is performed to increase precision in 684 * fixed-point calculations. 685 */ 686 u32 peak_rate; 687 688 /* maximum budget allotted to a bfq_queue before rescheduling */ 689 int bfq_max_budget; 690 691 /* 692 * List of all the bfq_queues active for a specific actuator 693 * on the device. Keeping active queues separate on a 694 * per-actuator basis helps implementing per-actuator 695 * injection more efficiently. 696 */ 697 struct list_head active_list[BFQ_MAX_ACTUATORS]; 698 /* list of all the bfq_queues idle on the device */ 699 struct list_head idle_list; 700 701 /* 702 * Timeout for async/sync requests; when it fires, requests 703 * are served in fifo order. 704 */ 705 u64 bfq_fifo_expire[2]; 706 /* weight of backward seeks wrt forward ones */ 707 unsigned int bfq_back_penalty; 708 /* maximum allowed backward seek */ 709 unsigned int bfq_back_max; 710 /* maximum idling time */ 711 u32 bfq_slice_idle; 712 713 /* user-configured max budget value (0 for auto-tuning) */ 714 int bfq_user_max_budget; 715 /* 716 * Timeout for bfq_queues to consume their budget; used to 717 * prevent seeky queues from imposing long latencies to 718 * sequential or quasi-sequential ones (this also implies that 719 * seeky queues cannot receive guarantees in the service 720 * domain; after a timeout they are charged for the time they 721 * have been in service, to preserve fairness among them, but 722 * without service-domain guarantees). 723 */ 724 unsigned int bfq_timeout; 725 726 /* 727 * Force device idling whenever needed to provide accurate 728 * service guarantees, without caring about throughput 729 * issues. CAVEAT: this may even increase latencies, in case 730 * of useless idling for processes that did stop doing I/O. 731 */ 732 bool strict_guarantees; 733 734 /* 735 * Last time at which a queue entered the current burst of 736 * queues being activated shortly after each other; for more 737 * details about this and the following parameters related to 738 * a burst of activations, see the comments on the function 739 * bfq_handle_burst. 740 */ 741 unsigned long last_ins_in_burst; 742 /* 743 * Reference time interval used to decide whether a queue has 744 * been activated shortly after @last_ins_in_burst. 745 */ 746 unsigned long bfq_burst_interval; 747 /* number of queues in the current burst of queue activations */ 748 int burst_size; 749 750 /* common parent entity for the queues in the burst */ 751 struct bfq_entity *burst_parent_entity; 752 /* Maximum burst size above which the current queue-activation 753 * burst is deemed as 'large'. 754 */ 755 unsigned long bfq_large_burst_thresh; 756 /* true if a large queue-activation burst is in progress */ 757 bool large_burst; 758 /* 759 * Head of the burst list (as for the above fields, more 760 * details in the comments on the function bfq_handle_burst). 761 */ 762 struct hlist_head burst_list; 763 764 /* if set to true, low-latency heuristics are enabled */ 765 bool low_latency; 766 /* 767 * Maximum factor by which the weight of a weight-raised queue 768 * is multiplied. 769 */ 770 unsigned int bfq_wr_coeff; 771 772 /* Maximum weight-raising duration for soft real-time processes */ 773 unsigned int bfq_wr_rt_max_time; 774 /* 775 * Minimum idle period after which weight-raising may be 776 * reactivated for a queue (in jiffies). 777 */ 778 unsigned int bfq_wr_min_idle_time; 779 /* 780 * Minimum period between request arrivals after which 781 * weight-raising may be reactivated for an already busy async 782 * queue (in jiffies). 783 */ 784 unsigned long bfq_wr_min_inter_arr_async; 785 786 /* Max service-rate for a soft real-time queue, in sectors/sec */ 787 unsigned int bfq_wr_max_softrt_rate; 788 /* 789 * Cached value of the product ref_rate*ref_wr_duration, used 790 * for computing the maximum duration of weight raising 791 * automatically. 792 */ 793 u64 rate_dur_prod; 794 795 /* fallback dummy bfqq for extreme OOM conditions */ 796 struct bfq_queue oom_bfqq; 797 798 spinlock_t lock; 799 800 /* 801 * bic associated with the task issuing current bio for 802 * merging. This and the next field are used as a support to 803 * be able to perform the bic lookup, needed by bio-merge 804 * functions, before the scheduler lock is taken, and thus 805 * avoid taking the request-queue lock while the scheduler 806 * lock is being held. 807 */ 808 struct bfq_io_cq *bio_bic; 809 /* bfqq associated with the task issuing current bio for merging */ 810 struct bfq_queue *bio_bfqq; 811 812 /* 813 * Depth limits used in bfq_limit_depth (see comments on the 814 * function) 815 */ 816 unsigned int word_depths[2][2]; 817 unsigned int full_depth_shift; 818 819 /* 820 * Number of independent actuators. This is equal to 1 in 821 * case of single-actuator drives. 822 */ 823 unsigned int num_actuators; 824 /* 825 * Disk independent access ranges for each actuator 826 * in this device. 827 */ 828 sector_t sector[BFQ_MAX_ACTUATORS]; 829 sector_t nr_sectors[BFQ_MAX_ACTUATORS]; 830 struct blk_independent_access_range ia_ranges[BFQ_MAX_ACTUATORS]; 831 832 /* 833 * If the number of I/O requests queued in the device for a 834 * given actuator is below next threshold, then the actuator 835 * is deemed as underutilized. If this condition is found to 836 * hold for some actuator upon a dispatch, but (i) the 837 * in-service queue does not contain I/O for that actuator, 838 * while (ii) some other queue does contain I/O for that 839 * actuator, then the head I/O request of the latter queue is 840 * returned (injected), instead of the head request of the 841 * currently in-service queue. 842 * 843 * We set the threshold, empirically, to the minimum possible 844 * value for which an actuator is fully utilized, or close to 845 * be fully utilized. By doing so, injected I/O 'steals' as 846 * few drive-queue slots as possibile to the in-service 847 * queue. This reduces as much as possible the probability 848 * that the service of I/O from the in-service bfq_queue gets 849 * delayed because of slot exhaustion, i.e., because all the 850 * slots of the drive queue are filled with I/O injected from 851 * other queues (NCQ provides for 32 slots). 852 */ 853 unsigned int actuator_load_threshold; 854}; 855 856enum bfqq_state_flags { 857 BFQQF_just_created = 0, /* queue just allocated */ 858 BFQQF_busy, /* has requests or is in service */ 859 BFQQF_wait_request, /* waiting for a request */ 860 BFQQF_non_blocking_wait_rq, /* 861 * waiting for a request 862 * without idling the device 863 */ 864 BFQQF_fifo_expire, /* FIFO checked in this slice */ 865 BFQQF_has_short_ttime, /* queue has a short think time */ 866 BFQQF_sync, /* synchronous queue */ 867 BFQQF_IO_bound, /* 868 * bfqq has timed-out at least once 869 * having consumed at most 2/10 of 870 * its budget 871 */ 872 BFQQF_in_large_burst, /* 873 * bfqq activated in a large burst, 874 * see comments to bfq_handle_burst. 875 */ 876 BFQQF_softrt_update, /* 877 * may need softrt-next-start 878 * update 879 */ 880 BFQQF_coop, /* bfqq is shared */ 881 BFQQF_split_coop, /* shared bfqq will be split */ 882}; 883 884#define BFQ_BFQQ_FNS(name) \ 885void bfq_mark_bfqq_##name(struct bfq_queue *bfqq); \ 886void bfq_clear_bfqq_##name(struct bfq_queue *bfqq); \ 887int bfq_bfqq_##name(const struct bfq_queue *bfqq); 888 889BFQ_BFQQ_FNS(just_created); 890BFQ_BFQQ_FNS(busy); 891BFQ_BFQQ_FNS(wait_request); 892BFQ_BFQQ_FNS(non_blocking_wait_rq); 893BFQ_BFQQ_FNS(fifo_expire); 894BFQ_BFQQ_FNS(has_short_ttime); 895BFQ_BFQQ_FNS(sync); 896BFQ_BFQQ_FNS(IO_bound); 897BFQ_BFQQ_FNS(in_large_burst); 898BFQ_BFQQ_FNS(coop); 899BFQ_BFQQ_FNS(split_coop); 900BFQ_BFQQ_FNS(softrt_update); 901#undef BFQ_BFQQ_FNS 902 903/* Expiration reasons. */ 904enum bfqq_expiration { 905 BFQQE_TOO_IDLE = 0, /* 906 * queue has been idling for 907 * too long 908 */ 909 BFQQE_BUDGET_TIMEOUT, /* budget took too long to be used */ 910 BFQQE_BUDGET_EXHAUSTED, /* budget consumed */ 911 BFQQE_NO_MORE_REQUESTS, /* the queue has no more requests */ 912 BFQQE_PREEMPTED /* preemption in progress */ 913}; 914 915struct bfq_stat { 916 struct percpu_counter cpu_cnt; 917 atomic64_t aux_cnt; 918}; 919 920struct bfqg_stats { 921 /* basic stats */ 922 struct blkg_rwstat bytes; 923 struct blkg_rwstat ios; 924#ifdef CONFIG_BFQ_CGROUP_DEBUG 925 /* number of ios merged */ 926 struct blkg_rwstat merged; 927 /* total time spent on device in ns, may not be accurate w/ queueing */ 928 struct blkg_rwstat service_time; 929 /* total time spent waiting in scheduler queue in ns */ 930 struct blkg_rwstat wait_time; 931 /* number of IOs queued up */ 932 struct blkg_rwstat queued; 933 /* total disk time and nr sectors dispatched by this group */ 934 struct bfq_stat time; 935 /* sum of number of ios queued across all samples */ 936 struct bfq_stat avg_queue_size_sum; 937 /* count of samples taken for average */ 938 struct bfq_stat avg_queue_size_samples; 939 /* how many times this group has been removed from service tree */ 940 struct bfq_stat dequeue; 941 /* total time spent waiting for it to be assigned a timeslice. */ 942 struct bfq_stat group_wait_time; 943 /* time spent idling for this blkcg_gq */ 944 struct bfq_stat idle_time; 945 /* total time with empty current active q with other requests queued */ 946 struct bfq_stat empty_time; 947 /* fields after this shouldn't be cleared on stat reset */ 948 u64 start_group_wait_time; 949 u64 start_idle_time; 950 u64 start_empty_time; 951 uint16_t flags; 952#endif /* CONFIG_BFQ_CGROUP_DEBUG */ 953}; 954 955#ifdef CONFIG_BFQ_GROUP_IOSCHED 956 957/* 958 * struct bfq_group_data - per-blkcg storage for the blkio subsystem. 959 * 960 * @ps: @blkcg_policy_storage that this structure inherits 961 * @weight: weight of the bfq_group 962 */ 963struct bfq_group_data { 964 /* must be the first member */ 965 struct blkcg_policy_data pd; 966 967 unsigned int weight; 968}; 969 970/** 971 * struct bfq_group - per (device, cgroup) data structure. 972 * @entity: schedulable entity to insert into the parent group sched_data. 973 * @sched_data: own sched_data, to contain child entities (they may be 974 * both bfq_queues and bfq_groups). 975 * @bfqd: the bfq_data for the device this group acts upon. 976 * @async_bfqq: array of async queues for all the tasks belonging to 977 * the group, one queue per ioprio value per ioprio_class, 978 * except for the idle class that has only one queue. 979 * @async_idle_bfqq: async queue for the idle class (ioprio is ignored). 980 * @my_entity: pointer to @entity, %NULL for the toplevel group; used 981 * to avoid too many special cases during group creation/ 982 * migration. 983 * @stats: stats for this bfqg. 984 * @active_entities: number of active entities belonging to the group; 985 * unused for the root group. Used to know whether there 986 * are groups with more than one active @bfq_entity 987 * (see the comments to the function 988 * bfq_bfqq_may_idle()). 989 * @rq_pos_tree: rbtree sorted by next_request position, used when 990 * determining if two or more queues have interleaving 991 * requests (see bfq_find_close_cooperator()). 992 * 993 * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup 994 * there is a set of bfq_groups, each one collecting the lower-level 995 * entities belonging to the group that are acting on the same device. 996 * 997 * Locking works as follows: 998 * o @bfqd is protected by the queue lock, RCU is used to access it 999 * from the readers. 1000 * o All the other fields are protected by the @bfqd queue lock. 1001 */ 1002struct bfq_group { 1003 /* must be the first member */ 1004 struct blkg_policy_data pd; 1005 1006 /* cached path for this blkg (see comments in bfq_bic_update_cgroup) */ 1007 char blkg_path[128]; 1008 1009 /* reference counter (see comments in bfq_bic_update_cgroup) */ 1010 refcount_t ref; 1011 1012 struct bfq_entity entity; 1013 struct bfq_sched_data sched_data; 1014 1015 struct bfq_data *bfqd; 1016 1017 struct bfq_queue *async_bfqq[2][IOPRIO_NR_LEVELS][BFQ_MAX_ACTUATORS]; 1018 struct bfq_queue *async_idle_bfqq[BFQ_MAX_ACTUATORS]; 1019 1020 struct bfq_entity *my_entity; 1021 1022 int active_entities; 1023 int num_queues_with_pending_reqs; 1024 1025 struct rb_root rq_pos_tree; 1026 1027 struct bfqg_stats stats; 1028}; 1029 1030#else 1031struct bfq_group { 1032 struct bfq_entity entity; 1033 struct bfq_sched_data sched_data; 1034 1035 struct bfq_queue *async_bfqq[2][IOPRIO_NR_LEVELS][BFQ_MAX_ACTUATORS]; 1036 struct bfq_queue *async_idle_bfqq[BFQ_MAX_ACTUATORS]; 1037 1038 struct rb_root rq_pos_tree; 1039}; 1040#endif 1041 1042/* --------------- main algorithm interface ----------------- */ 1043 1044#define BFQ_SERVICE_TREE_INIT ((struct bfq_service_tree) \ 1045 { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 }) 1046 1047extern const int bfq_timeout; 1048 1049struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync, 1050 unsigned int actuator_idx); 1051void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, bool is_sync, 1052 unsigned int actuator_idx); 1053struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic); 1054void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq); 1055void bfq_weights_tree_add(struct bfq_queue *bfqq); 1056void bfq_weights_tree_remove(struct bfq_queue *bfqq); 1057void bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq, 1058 bool compensate, enum bfqq_expiration reason); 1059void bfq_put_queue(struct bfq_queue *bfqq); 1060void bfq_put_cooperator(struct bfq_queue *bfqq); 1061void bfq_end_wr_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg); 1062void bfq_release_process_ref(struct bfq_data *bfqd, struct bfq_queue *bfqq); 1063void bfq_schedule_dispatch(struct bfq_data *bfqd); 1064void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg); 1065 1066/* ------------ end of main algorithm interface -------------- */ 1067 1068/* ---------------- cgroups-support interface ---------------- */ 1069 1070void bfqg_stats_update_legacy_io(struct request_queue *q, struct request *rq); 1071void bfqg_stats_update_io_remove(struct bfq_group *bfqg, blk_opf_t opf); 1072void bfqg_stats_update_io_merged(struct bfq_group *bfqg, blk_opf_t opf); 1073void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns, 1074 u64 io_start_time_ns, blk_opf_t opf); 1075void bfqg_stats_update_dequeue(struct bfq_group *bfqg); 1076void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg); 1077void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, 1078 struct bfq_group *bfqg); 1079 1080#ifdef CONFIG_BFQ_CGROUP_DEBUG 1081void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq, 1082 blk_opf_t opf); 1083void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg); 1084void bfqg_stats_update_idle_time(struct bfq_group *bfqg); 1085void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg); 1086#endif 1087 1088void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg); 1089void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio); 1090void bfq_end_wr_async(struct bfq_data *bfqd); 1091struct bfq_group *bfq_bio_bfqg(struct bfq_data *bfqd, struct bio *bio); 1092struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg); 1093struct bfq_group *bfqq_group(struct bfq_queue *bfqq); 1094struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node); 1095void bfqg_and_blkg_put(struct bfq_group *bfqg); 1096 1097#ifdef CONFIG_BFQ_GROUP_IOSCHED 1098extern struct cftype bfq_blkcg_legacy_files[]; 1099extern struct cftype bfq_blkg_files[]; 1100extern struct blkcg_policy blkcg_policy_bfq; 1101#endif 1102 1103/* ------------- end of cgroups-support interface ------------- */ 1104 1105/* - interface of the internal hierarchical B-WF2Q+ scheduler - */ 1106 1107#ifdef CONFIG_BFQ_GROUP_IOSCHED 1108/* both next loops stop at one of the child entities of the root group */ 1109#define for_each_entity(entity) \ 1110 for (; entity ; entity = entity->parent) 1111 1112/* 1113 * For each iteration, compute parent in advance, so as to be safe if 1114 * entity is deallocated during the iteration. Such a deallocation may 1115 * happen as a consequence of a bfq_put_queue that frees the bfq_queue 1116 * containing entity. 1117 */ 1118#define for_each_entity_safe(entity, parent) \ 1119 for (; entity && ({ parent = entity->parent; 1; }); entity = parent) 1120 1121#else /* CONFIG_BFQ_GROUP_IOSCHED */ 1122/* 1123 * Next two macros are fake loops when cgroups support is not 1124 * enabled. I fact, in such a case, there is only one level to go up 1125 * (to reach the root group). 1126 */ 1127#define for_each_entity(entity) \ 1128 for (; entity ; entity = NULL) 1129 1130#define for_each_entity_safe(entity, parent) \ 1131 for (parent = NULL; entity ; entity = parent) 1132#endif /* CONFIG_BFQ_GROUP_IOSCHED */ 1133 1134struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity); 1135unsigned int bfq_tot_busy_queues(struct bfq_data *bfqd); 1136struct bfq_service_tree *bfq_entity_service_tree(struct bfq_entity *entity); 1137struct bfq_entity *bfq_entity_of(struct rb_node *node); 1138unsigned short bfq_ioprio_to_weight(int ioprio); 1139void bfq_put_idle_entity(struct bfq_service_tree *st, 1140 struct bfq_entity *entity); 1141struct bfq_service_tree * 1142__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st, 1143 struct bfq_entity *entity, 1144 bool update_class_too); 1145void bfq_bfqq_served(struct bfq_queue *bfqq, int served); 1146void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq, 1147 unsigned long time_ms); 1148bool __bfq_deactivate_entity(struct bfq_entity *entity, 1149 bool ins_into_idle_tree); 1150bool next_queue_may_preempt(struct bfq_data *bfqd); 1151struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd); 1152bool __bfq_bfqd_reset_in_service(struct bfq_data *bfqd); 1153void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, 1154 bool ins_into_idle_tree, bool expiration); 1155void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq); 1156void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, 1157 bool expiration); 1158void bfq_del_bfqq_busy(struct bfq_queue *bfqq, bool expiration); 1159void bfq_add_bfqq_busy(struct bfq_queue *bfqq); 1160void bfq_add_bfqq_in_groups_with_pending_reqs(struct bfq_queue *bfqq); 1161void bfq_del_bfqq_in_groups_with_pending_reqs(struct bfq_queue *bfqq); 1162 1163/* --------------- end of interface of B-WF2Q+ ---------------- */ 1164 1165/* Logging facilities. */ 1166static inline void bfq_bfqq_name(struct bfq_queue *bfqq, char *str, int len) 1167{ 1168 char type = bfq_bfqq_sync(bfqq) ? 'S' : 'A'; 1169 1170 if (bfqq->pid != -1) 1171 snprintf(str, len, "bfq%d%c", bfqq->pid, type); 1172 else 1173 snprintf(str, len, "bfqSHARED-%c", type); 1174} 1175 1176#ifdef CONFIG_BFQ_GROUP_IOSCHED 1177struct bfq_group *bfqq_group(struct bfq_queue *bfqq); 1178 1179#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \ 1180 char pid_str[MAX_BFQQ_NAME_LENGTH]; \ 1181 if (likely(!blk_trace_note_message_enabled((bfqd)->queue))) \ 1182 break; \ 1183 bfq_bfqq_name((bfqq), pid_str, MAX_BFQQ_NAME_LENGTH); \ 1184 blk_add_cgroup_trace_msg((bfqd)->queue, \ 1185 &bfqg_to_blkg(bfqq_group(bfqq))->blkcg->css, \ 1186 "%s " fmt, pid_str, ##args); \ 1187} while (0) 1188 1189#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do { \ 1190 blk_add_cgroup_trace_msg((bfqd)->queue, \ 1191 &bfqg_to_blkg(bfqg)->blkcg->css, fmt, ##args); \ 1192} while (0) 1193 1194#else /* CONFIG_BFQ_GROUP_IOSCHED */ 1195 1196#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \ 1197 char pid_str[MAX_BFQQ_NAME_LENGTH]; \ 1198 if (likely(!blk_trace_note_message_enabled((bfqd)->queue))) \ 1199 break; \ 1200 bfq_bfqq_name((bfqq), pid_str, MAX_BFQQ_NAME_LENGTH); \ 1201 blk_add_trace_msg((bfqd)->queue, "%s " fmt, pid_str, ##args); \ 1202} while (0) 1203#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do {} while (0) 1204 1205#endif /* CONFIG_BFQ_GROUP_IOSCHED */ 1206 1207#define bfq_log(bfqd, fmt, args...) \ 1208 blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args) 1209 1210#endif /* _BFQ_H */ 1211