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