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1/* SPDX-License-Identifier: GPL-2.0-or-later */2/*3 * Header file for the BFQ I/O scheduler: data structures and4 * prototypes of interface functions among BFQ components.5 */6#ifndef _BFQ_H7#define _BFQ_H8 9#include <linux/blktrace_api.h>10#include <linux/hrtimer.h>11 12#include "blk-cgroup-rwstat.h"13 14#define BFQ_IOPRIO_CLASSES 315#define BFQ_CL_IDLE_TIMEOUT (HZ/5)16 17#define BFQ_MIN_WEIGHT 118#define BFQ_MAX_WEIGHT 100019#define BFQ_WEIGHT_CONVERSION_COEFF 1020 21#define BFQ_DEFAULT_QUEUE_IOPRIO 422 23#define BFQ_DEFAULT_GRP_IOPRIO 024#define BFQ_DEFAULT_GRP_CLASS IOPRIO_CLASS_BE25 26#define MAX_BFQQ_NAME_LENGTH 1627 28/*29 * Soft real-time applications are extremely more latency sensitive30 * than interactive ones. Over-raise the weight of the former to31 * privilege them against the latter.32 */33#define BFQ_SOFTRT_WEIGHT_FACTOR 10034 35/*36 * Maximum number of actuators supported. This constant is used simply37 * to define the size of the static array that will contain38 * per-actuator data. The current value is hopefully a good upper39 * bound to the possible number of actuators of any actual drive.40 */41#define BFQ_MAX_ACTUATORS 842 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. Each49 * ioprio_class has its own independent scheduler, and so its own50 * bfq_service_tree. All the fields are protected by the queue lock51 * 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 three74 * ioprio_classes, and can be used either as a toplevel queue or as an75 * intermediate queue in a hierarchical setup.76 *77 * The supported ioprio_classes are the same as in CFQ, in descending78 * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE.79 * Requests from higher priority queues are served before all the80 * requests from lower priority queues; among requests of the same81 * queue requests are served according to B-WF2Q+.82 *83 * The schedule is implemented by the service trees, plus the field84 * @next_in_service, which points to the entity on the active trees85 * that will be served next, if 1) no changes in the schedule occurs86 * before the current in-service entity is expired, 2) the in-service87 * queue becomes idle when it expires, and 3) if the entity pointed by88 * in_service_entity is not a queue, then the in-service child entity89 * of the entity pointed by in_service_entity becomes idle on90 * expiration. This peculiar definition allows for the following91 * optimization, not yet exploited: while a given entity is still in92 * service, we already know which is the best candidate for next93 * service among the other active entities in the same parent94 * entity. We can then quickly compare the timestamps of the95 * 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 queues113 * 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 the128 * cgroup hierarchy) or a bfq_group into the upper level scheduler. Each129 * entity belongs to the sched_data of the parent group in the cgroup130 * hierarchy. Non-leaf entities have also their own sched_data, stored131 * in @my_sched_data.132 *133 * Each entity stores independently its priority values; this would134 * allow different weights on different devices, but this135 * functionality is not exported to userspace by now. Priorities and136 * weights are updated lazily, first storing the new values into the137 * new_* fields, then setting the @prio_changed flag. As soon as138 * there is a transition in the entity state that allows the priority139 * update to take place the effective and the requested priority140 * values are synchronized.141 *142 * Unless cgroups are used, the weight value is calculated from the143 * ioprio to export the same interface as CFQ. When dealing with144 * "well-behaved" queues (i.e., queues that do not spend too much145 * time to consume their budget and have true sequential behavior, and146 * when there are no external factors breaking anticipation) the147 * relative weights at each level of the cgroups hierarchy should be148 * guaranteed. All the fields are protected by the queue lock of the149 * 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 or157 * 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 this169 * entity; used for O(log N) lookups into active trees170 */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 of183 * 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 associated198 * 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_IOSCHED208 /* flag, set if the entity is counted in groups_with_pending_reqs */209 bool in_groups_with_pending_reqs;210#endif211 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 an237 * io_context or more, if it is async or shared between cooperating238 * processes. Besides, it contains I/O requests for only one actuator239 * (an io_context is associated with a different bfq_queue for each240 * actuator it generates I/O for). @cgroup holds a reference to the241 * cgroup, to be sure that it does not disappear while a bfqq still242 * references it (mostly to avoid races between request issuing and243 * task migration followed by cgroup destruction). All the fields are244 * 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 more268 * 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 and325 * arrival, such that the queue becomes idle after the326 * completion, but the next request arrives within an idle327 * time slice; used only if the queue's IO_bound flag has been328 * 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 %NULL337 * 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 is345 * enqueued after this time instant in an idle @bfq_queue with346 * no outstanding requests, then the task associated with the347 * queue it is deemed as soft real-time (see the comments on348 * 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 if353 * the @bfq-queue is being weight-raised, otherwise354 * 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 to361 * backlogged.362 */363 unsigned long last_idle_bklogged;364 /*365 * Cumulative service received from the @bfq_queue since the366 * last transition from idle to backlogged.367 */368 unsigned long service_from_backlogged;369 /*370 * Cumulative service received from the @bfq_queue since its371 * 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 rt377 */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 the387 * queue Q such that this queue happens to get new I/O right388 * after some I/O request of Q is completed. For details, see389 * the comments on the choice of the queue for injection in390 * 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 waker405 * queue. This list is used to reset the waker_bfqq pointer in406 * 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_cq416*/417struct bfq_iocq_bfqq_data {418 /*419 * Snapshot of the has_short_time flag before merging; taken420 * to remember its values while the queue is merged, so as to421 * 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 bound426 * 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 the435 * field keeping the queue's belonging to a large burst436 */437 bool saved_in_large_burst;438 /*439 * True if the queue belonged to a burst list before its merge440 * with another cooperating queue.441 */442 bool was_in_burst_list;443 444 /*445 * Save the weight when a merge occurs, to be able446 * to restore it in case of split. If the weight is not447 * correctly resumed when the queue is recycled,448 * then the weight of the recycled queue could differ449 * 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 async482 * queues, second row sync queues. Each row contains one483 * column for each actuator. An I/O request generated by the484 * process is inserted into the queue pointed by bfqq[i][j] if485 * the request is to be served by the j-th actuator of the486 * drive, where i==0 or i==1, depending on whether the request487 * is async or sync. So there is a distinct queue for each488 * 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_IOSCHED494 uint64_t blkcg_serial_nr; /* the current blkcg serial */495#endif496 497 /*498 * Persistent data for associated synchronous process queues499 * (one queue per actuator, see field bfqq above). In500 * 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 by523 * weight. Used to keep track of whether all @bfq_queues have524 * the same weight. The tree contains one counter for each525 * distinct weight associated to some active and not526 * weight-raised @bfq_queue (see the comments to the functions527 * bfq_weights_tree_[add|remove] for further details).528 */529 struct rb_root_cached queue_weights_tree;530 531#ifdef CONFIG_BFQ_GROUP_IOSCHED532 /*533 * Number of groups with at least one process that534 * has at least one request waiting for completion. Note that535 * this accounts for also requests already dispatched, but not536 * yet completed. Therefore this number of groups may differ537 * (be larger) than the number of active groups, as a group is538 * considered active only if its corresponding entity has539 * queues with at least one request queued. This540 * number is used to decide whether a scenario is symmetric.541 * For a detailed explanation see comments on the computation542 * of the variable asymmetric_scenario in the function543 * bfq_better_to_idle().544 *545 * However, it is hard to compute this number exactly, for546 * groups with multiple processes. Consider a group547 * that is inactive, i.e., that has no process with548 * pending I/O inside BFQ queues. Then suppose that549 * num_groups_with_pending_reqs is still accounting for this550 * group, because the group has processes with some551 * I/O request still in flight. num_groups_with_pending_reqs552 * should be decremented when the in-flight request of the553 * last process is finally completed (assuming that554 * nothing else has changed for the group in the meantime, in555 * terms of composition of the group and active/inactive state of child556 * groups and processes). To accomplish this, an additional557 * pending-request counter must be added to entities, and must558 * be updated correctly. To avoid this additional field and operations,559 * we resort to the following tradeoff between simplicity and560 * accuracy: for an inactive group that is still counted in561 * num_groups_with_pending_reqs, we decrement562 * num_groups_with_pending_reqs when the first563 * process of the group remains with no request waiting for564 * completion.565 *566 * Even this simpler decrement strategy requires a little567 * carefulness: to avoid multiple decrements, we flag a group,568 * more precisely an entity representing a group, as still569 * counted in num_groups_with_pending_reqs when it becomes570 * inactive. Then, when the first queue of the571 * entity remains with no request waiting for completion,572 * num_groups_with_pending_reqs is decremented, and this flag573 * is reset. After this flag is reset for the entity,574 * num_groups_with_pending_reqs won't be decremented any575 * longer in case a new queue of the entity remains576 * with no request waiting for completion.577 */578 unsigned int num_groups_with_pending_reqs;579#endif580 581 /*582 * Per-class (RT, BE, IDLE) number of bfq_queues containing583 * requests (including the queue in service, even if it is584 * 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 completion595 * for each actuator596 */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 last604 * @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 from617 * 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 time644 * of a just-arrived first I/O request (see645 * bfq_update_inject_limit()). This will cause the setting of646 * waited_rq when the request is finally dispatched.647 */648 bool wait_dispatch;649 /*650 * If set, then bfq_update_inject_limit() is invoked when651 * 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 in682 * [(sectors/usec) / 2^BFQ_RATE_SHIFT]. The left-shift by683 * BFQ_RATE_SHIFT is performed to increase precision in684 * 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 actuator693 * on the device. Keeping active queues separate on a694 * per-actuator basis helps implementing per-actuator695 * 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, requests703 * 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 to717 * prevent seeky queues from imposing long latencies to718 * sequential or quasi-sequential ones (this also implies that719 * seeky queues cannot receive guarantees in the service720 * domain; after a timeout they are charged for the time they721 * have been in service, to preserve fairness among them, but722 * without service-domain guarantees).723 */724 unsigned int bfq_timeout;725 726 /*727 * Force device idling whenever needed to provide accurate728 * service guarantees, without caring about throughput729 * issues. CAVEAT: this may even increase latencies, in case730 * 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 of736 * queues being activated shortly after each other; for more737 * details about this and the following parameters related to738 * a burst of activations, see the comments on the function739 * bfq_handle_burst.740 */741 unsigned long last_ins_in_burst;742 /*743 * Reference time interval used to decide whether a queue has744 * 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-activation753 * 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, more760 * 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 queue768 * 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 be776 * reactivated for a queue (in jiffies).777 */778 unsigned int bfq_wr_min_idle_time;779 /*780 * Minimum period between request arrivals after which781 * weight-raising may be reactivated for an already busy async782 * 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, used790 * for computing the maximum duration of weight raising791 * 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 for802 * merging. This and the next field are used as a support to803 * be able to perform the bic lookup, needed by bio-merge804 * functions, before the scheduler lock is taken, and thus805 * avoid taking the request-queue lock while the scheduler806 * 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 the814 * 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 in821 * case of single-actuator drives.822 */823 unsigned int num_actuators;824 /*825 * Disk independent access ranges for each actuator826 * 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 a834 * given actuator is below next threshold, then the actuator835 * is deemed as underutilized. If this condition is found to836 * hold for some actuator upon a dispatch, but (i) the837 * in-service queue does not contain I/O for that actuator,838 * while (ii) some other queue does contain I/O for that839 * actuator, then the head I/O request of the latter queue is840 * returned (injected), instead of the head request of the841 * currently in-service queue.842 *843 * We set the threshold, empirically, to the minimum possible844 * value for which an actuator is fully utilized, or close to845 * be fully utilized. By doing so, injected I/O 'steals' as846 * few drive-queue slots as possibile to the in-service847 * queue. This reduces as much as possible the probability848 * that the service of I/O from the in-service bfq_queue gets849 * delayed because of slot exhaustion, i.e., because all the850 * slots of the drive queue are filled with I/O injected from851 * 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 request862 * without idling the device863 */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 once869 * having consumed at most 2/10 of870 * its budget871 */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-start878 * update879 */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_FNS902 903/* Expiration reasons. */904enum bfqq_expiration {905 BFQQE_TOO_IDLE = 0, /*906 * queue has been idling for907 * too long908 */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_DEBUG925 /* 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_IOSCHED956 957/*958 * struct bfq_group_data - per-blkcg storage for the blkio subsystem.959 *960 * @ps: @blkcg_policy_storage that this structure inherits961 * @weight: weight of the bfq_group962 */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 be974 * 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 to977 * 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; used981 * 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 there986 * are groups with more than one active @bfq_entity987 * (see the comments to the function988 * bfq_bfqq_may_idle()).989 * @rq_pos_tree: rbtree sorted by next_request position, used when990 * determining if two or more queues have interleaving991 * requests (see bfq_find_close_cooperator()).992 *993 * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup994 * there is a set of bfq_groups, each one collecting the lower-level995 * 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 it999 * 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 /* reference counter (see comments in bfq_bic_update_cgroup) */1007 refcount_t ref;1008 1009 struct bfq_entity entity;1010 struct bfq_sched_data sched_data;1011 1012 struct bfq_data *bfqd;1013 1014 struct bfq_queue *async_bfqq[2][IOPRIO_NR_LEVELS][BFQ_MAX_ACTUATORS];1015 struct bfq_queue *async_idle_bfqq[BFQ_MAX_ACTUATORS];1016 1017 struct bfq_entity *my_entity;1018 1019 int active_entities;1020 int num_queues_with_pending_reqs;1021 1022 struct rb_root rq_pos_tree;1023 1024 struct bfqg_stats stats;1025};1026 1027#else1028struct bfq_group {1029 struct bfq_entity entity;1030 struct bfq_sched_data sched_data;1031 1032 struct bfq_queue *async_bfqq[2][IOPRIO_NR_LEVELS][BFQ_MAX_ACTUATORS];1033 struct bfq_queue *async_idle_bfqq[BFQ_MAX_ACTUATORS];1034 1035 struct rb_root rq_pos_tree;1036};1037#endif1038 1039/* --------------- main algorithm interface ----------------- */1040 1041#define BFQ_SERVICE_TREE_INIT ((struct bfq_service_tree) \1042 { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })1043 1044extern const int bfq_timeout;1045 1046struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync,1047 unsigned int actuator_idx);1048void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, bool is_sync,1049 unsigned int actuator_idx);1050struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic);1051void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq);1052void bfq_weights_tree_add(struct bfq_queue *bfqq);1053void bfq_weights_tree_remove(struct bfq_queue *bfqq);1054void bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq,1055 bool compensate, enum bfqq_expiration reason);1056void bfq_put_queue(struct bfq_queue *bfqq);1057void bfq_put_cooperator(struct bfq_queue *bfqq);1058void bfq_end_wr_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);1059void bfq_release_process_ref(struct bfq_data *bfqd, struct bfq_queue *bfqq);1060void bfq_schedule_dispatch(struct bfq_data *bfqd);1061void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);1062 1063/* ------------ end of main algorithm interface -------------- */1064 1065/* ---------------- cgroups-support interface ---------------- */1066 1067void bfqg_stats_update_legacy_io(struct request_queue *q, struct request *rq);1068void bfqg_stats_update_io_remove(struct bfq_group *bfqg, blk_opf_t opf);1069void bfqg_stats_update_io_merged(struct bfq_group *bfqg, blk_opf_t opf);1070void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns,1071 u64 io_start_time_ns, blk_opf_t opf);1072void bfqg_stats_update_dequeue(struct bfq_group *bfqg);1073void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg);1074void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,1075 struct bfq_group *bfqg);1076 1077#ifdef CONFIG_BFQ_CGROUP_DEBUG1078void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,1079 blk_opf_t opf);1080void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg);1081void bfqg_stats_update_idle_time(struct bfq_group *bfqg);1082void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg);1083#endif1084 1085void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg);1086void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio);1087void bfq_end_wr_async(struct bfq_data *bfqd);1088struct bfq_group *bfq_bio_bfqg(struct bfq_data *bfqd, struct bio *bio);1089struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);1090struct bfq_group *bfqq_group(struct bfq_queue *bfqq);1091struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node);1092void bfqg_and_blkg_put(struct bfq_group *bfqg);1093 1094#ifdef CONFIG_BFQ_GROUP_IOSCHED1095extern struct cftype bfq_blkcg_legacy_files[];1096extern struct cftype bfq_blkg_files[];1097extern struct blkcg_policy blkcg_policy_bfq;1098#endif1099 1100/* ------------- end of cgroups-support interface ------------- */1101 1102/* - interface of the internal hierarchical B-WF2Q+ scheduler - */1103 1104#ifdef CONFIG_BFQ_GROUP_IOSCHED1105/* both next loops stop at one of the child entities of the root group */1106#define for_each_entity(entity) \1107 for (; entity ; entity = entity->parent)1108 1109/*1110 * For each iteration, compute parent in advance, so as to be safe if1111 * entity is deallocated during the iteration. Such a deallocation may1112 * happen as a consequence of a bfq_put_queue that frees the bfq_queue1113 * containing entity.1114 */1115#define for_each_entity_safe(entity, parent) \1116 for (; entity && ({ parent = entity->parent; 1; }); entity = parent)1117 1118#else /* CONFIG_BFQ_GROUP_IOSCHED */1119/*1120 * Next two macros are fake loops when cgroups support is not1121 * enabled. I fact, in such a case, there is only one level to go up1122 * (to reach the root group).1123 */1124#define for_each_entity(entity) \1125 for (; entity ; entity = NULL)1126 1127#define for_each_entity_safe(entity, parent) \1128 for (parent = NULL; entity ; entity = parent)1129#endif /* CONFIG_BFQ_GROUP_IOSCHED */1130 1131struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);1132unsigned int bfq_tot_busy_queues(struct bfq_data *bfqd);1133struct bfq_service_tree *bfq_entity_service_tree(struct bfq_entity *entity);1134struct bfq_entity *bfq_entity_of(struct rb_node *node);1135unsigned short bfq_ioprio_to_weight(int ioprio);1136void bfq_put_idle_entity(struct bfq_service_tree *st,1137 struct bfq_entity *entity);1138struct bfq_service_tree *1139__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,1140 struct bfq_entity *entity,1141 bool update_class_too);1142void bfq_bfqq_served(struct bfq_queue *bfqq, int served);1143void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq,1144 unsigned long time_ms);1145bool __bfq_deactivate_entity(struct bfq_entity *entity,1146 bool ins_into_idle_tree);1147bool next_queue_may_preempt(struct bfq_data *bfqd);1148struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd);1149bool __bfq_bfqd_reset_in_service(struct bfq_data *bfqd);1150void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,1151 bool ins_into_idle_tree, bool expiration);1152void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);1153void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,1154 bool expiration);1155void bfq_del_bfqq_busy(struct bfq_queue *bfqq, bool expiration);1156void bfq_add_bfqq_busy(struct bfq_queue *bfqq);1157void bfq_add_bfqq_in_groups_with_pending_reqs(struct bfq_queue *bfqq);1158void bfq_del_bfqq_in_groups_with_pending_reqs(struct bfq_queue *bfqq);1159void bfq_reassign_last_bfqq(struct bfq_queue *cur_bfqq,1160 struct bfq_queue *new_bfqq);1161 1162/* --------------- end of interface of B-WF2Q+ ---------------- */1163 1164/* Logging facilities. */1165static inline void bfq_bfqq_name(struct bfq_queue *bfqq, char *str, int len)1166{1167 char type = bfq_bfqq_sync(bfqq) ? 'S' : 'A';1168 1169 if (bfqq->pid != -1)1170 snprintf(str, len, "bfq%d%c", bfqq->pid, type);1171 else1172 snprintf(str, len, "bfqSHARED-%c", type);1173}1174 1175#ifdef CONFIG_BFQ_GROUP_IOSCHED1176struct bfq_group *bfqq_group(struct bfq_queue *bfqq);1177 1178#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \1179 char pid_str[MAX_BFQQ_NAME_LENGTH]; \1180 if (likely(!blk_trace_note_message_enabled((bfqd)->queue))) \1181 break; \1182 bfq_bfqq_name((bfqq), pid_str, MAX_BFQQ_NAME_LENGTH); \1183 blk_add_cgroup_trace_msg((bfqd)->queue, \1184 &bfqg_to_blkg(bfqq_group(bfqq))->blkcg->css, \1185 "%s " fmt, pid_str, ##args); \1186} while (0)1187 1188#else /* CONFIG_BFQ_GROUP_IOSCHED */1189 1190#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \1191 char pid_str[MAX_BFQQ_NAME_LENGTH]; \1192 if (likely(!blk_trace_note_message_enabled((bfqd)->queue))) \1193 break; \1194 bfq_bfqq_name((bfqq), pid_str, MAX_BFQQ_NAME_LENGTH); \1195 blk_add_trace_msg((bfqd)->queue, "%s " fmt, pid_str, ##args); \1196} while (0)1197 1198#endif /* CONFIG_BFQ_GROUP_IOSCHED */1199 1200#define bfq_log(bfqd, fmt, args...) \1201 blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)1202 1203#endif /* _BFQ_H */1204