block/bfq-iosched.h

   1 /*
   2  * Header file for the BFQ I/O scheduler: data structures and
   3  * prototypes of interface functions among BFQ components.
   4  *
   5  *  This program is free software; you can redistribute it and/or
   6  *  modify it under the terms of the GNU General Public License as
   7  *  published by the Free Software Foundation; either version 2 of the
   8  *  License, or (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  *  General Public License for more details.
  14  */
  15 #ifndef _BFQ_H
  16 #define _BFQ_H
  17
  18 #include <linux/blktrace_api.h>
  19 #include <linux/hrtimer.h>
  20 #include <linux/blk-cgroup.h>
  21
  22 #define BFQ_IOPRIO_CLASSES      3
  23 #define BFQ_CL_IDLE_TIMEOUT     (HZ/5)
  24
  25 #define BFQ_MIN_WEIGHT                  1
  26 #define BFQ_MAX_WEIGHT                  1000
  27 #define BFQ_WEIGHT_CONVERSION_COEFF     10
  28
  29 #define BFQ_DEFAULT_QUEUE_IOPRIO        4
  30
  31 #define BFQ_WEIGHT_LEGACY_DFL   100
  32 #define BFQ_DEFAULT_GRP_IOPRIO  0
  33 #define BFQ_DEFAULT_GRP_CLASS   IOPRIO_CLASS_BE
  34
  35 /*
  36  * Soft real-time applications are extremely more latency sensitive
  37  * than interactive ones. Over-raise the weight of the former to
  38  * privilege them against the latter.
  39  */
  40 #define BFQ_SOFTRT_WEIGHT_FACTOR        100
  41
  42 struct bfq_entity;
  43
  44 /**
  45  * struct bfq_service_tree - per ioprio_class service tree.
  46  *
  47  * Each service tree represents a B-WF2Q+ scheduler on its own.  Each
  48  * ioprio_class has its own independent scheduler, and so its own
  49  * bfq_service_tree.  All the fields are protected by the queue lock
  50  * of the containing bfqd.
  51  */
  52 struct bfq_service_tree {
  53         /* tree for active entities (i.e., those backlogged) */
  54         struct rb_root active;
  55         /* tree for idle entities (i.e., not backlogged, with V < F_i)*/
  56         struct rb_root idle;
  57
  58         /* idle entity with minimum F_i */
  59         struct bfq_entity *first_idle;
  60         /* idle entity with maximum F_i */
  61         struct bfq_entity *last_idle;
  62
  63         /* scheduler virtual time */
  64         u64 vtime;
  65         /* scheduler weight sum; active and idle entities contribute to it */
  66         unsigned long wsum;
  67 };
  68
  69 /**
  70  * struct bfq_sched_data - multi-class scheduler.
  71  *
  72  * bfq_sched_data is the basic scheduler queue.  It supports three
  73  * ioprio_classes, and can be used either as a toplevel queue or as an
  74  * intermediate queue in a hierarchical setup.
  75  *
  76  * The supported ioprio_classes are the same as in CFQ, in descending
  77  * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE.
  78  * Requests from higher priority queues are served before all the
  79  * requests from lower priority queues; among requests of the same
  80  * queue requests are served according to B-WF2Q+.
  81  *
  82  * The schedule is implemented by the service trees, plus the field
  83  * @next_in_service, which points to the entity on the active trees
  84  * that will be served next, if 1) no changes in the schedule occurs
  85  * before the current in-service entity is expired, 2) the in-service
  86  * queue becomes idle when it expires, and 3) if the entity pointed by
  87  * in_service_entity is not a queue, then the in-service child entity
  88  * of the entity pointed by in_service_entity becomes idle on
  89  * expiration. This peculiar definition allows for the following
  90  * optimization, not yet exploited: while a given entity is still in
  91  * service, we already know which is the best candidate for next
  92  * service among the other active entitities in the same parent
  93  * entity. We can then quickly compare the timestamps of the
  94  * in-service entity with those of such best candidate.
  95  *
  96  * All fields are protected by the lock of the containing bfqd.
  97  */
  98 struct bfq_sched_data {
  99         /* entity in service */
 100         struct bfq_entity *in_service_entity;
 101         /* head-of-line entity (see comments above) */
 102         struct bfq_entity *next_in_service;
 103         /* array of service trees, one per ioprio_class */
 104         struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES];
 105         /* last time CLASS_IDLE was served */
 106         unsigned long bfq_class_idle_last_service;
 107
 108 };
 109
 110 /**
 111  * struct bfq_weight_counter - counter of the number of all active entities
 112  *                             with a given weight.
 113  */
 114 struct bfq_weight_counter {
 115         unsigned int weight; /* weight of the entities this counter refers to */
 116         unsigned int num_active; /* nr of active entities with this weight */
 117         /*
 118          * Weights tree member (see bfq_data's @queue_weights_tree and
 119          * @group_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  */
 151 struct bfq_entity {
 152         /* service_tree member */
 153         struct rb_node rb_node;
 154         /* pointer to the weight counter associated with this entity */
 155         struct bfq_weight_counter *weight_counter;
 156
 157         /*
 158          * Flag, true if the entity is on a tree (either the active or
 159          * the idle one of its service_tree) or is in service.
 160          */
 161         bool on_st;
 162
 163         /* B-WF2Q+ start and finish timestamps [sectors/weight] */
 164         u64 start, finish;
 165
 166         /* tree the entity is enqueued into; %NULL if not on a tree */
 167         struct rb_root *tree;
 168
 169         /*
 170          * minimum start time of the (active) subtree rooted at this
 171          * entity; used for O(log N) lookups into active trees
 172          */
 173         u64 min_start;
 174
 175         /* amount of service received during the last service slot */
 176         int service;
 177
 178         /* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */
 179         int budget;
 180
 181         /* weight of the queue */
 182         int weight;
 183         /* next weight if a change is in progress */
 184         int new_weight;
 185
 186         /* original weight, used to implement weight boosting */
 187         int orig_weight;
 188
 189         /* parent entity, for hierarchical scheduling */
 190         struct bfq_entity *parent;
 191
 192         /*
 193          * For non-leaf nodes in the hierarchy, the associated
 194          * scheduler queue, %NULL on leaf nodes.
 195          */
 196         struct bfq_sched_data *my_sched_data;
 197         /* the scheduler queue this entity belongs to */
 198         struct bfq_sched_data *sched_data;
 199
 200         /* flag, set to request a weight, ioprio or ioprio_class change  */
 201         int prio_changed;
 202 };
 203
 204 struct bfq_group;
 205
 206 /**
 207  * struct bfq_ttime - per process thinktime stats.
 208  */
 209 struct bfq_ttime {
 210         /* completion time of the last request */
 211         u64 last_end_request;
 212
 213         /* total process thinktime */
 214         u64 ttime_total;
 215         /* number of thinktime samples */
 216         unsigned long ttime_samples;
 217         /* average process thinktime */
 218         u64 ttime_mean;
 219 };
 220
 221 /**
 222  * struct bfq_queue - leaf schedulable entity.
 223  *
 224  * A bfq_queue is a leaf request queue; it can be associated with an
 225  * io_context or more, if it  is  async or shared  between  cooperating
 226  * processes. @cgroup holds a reference to the cgroup, to be sure that it
 227  * does not disappear while a bfqq still references it (mostly to avoid
 228  * races between request issuing and task migration followed by cgroup
 229  * destruction).
 230  * All the fields are protected by the queue lock of the containing bfqd.
 231  */
 232 struct bfq_queue {
 233         /* reference counter */
 234         int ref;
 235         /* parent bfq_data */
 236         struct bfq_data *bfqd;
 237
 238         /* current ioprio and ioprio class */
 239         unsigned short ioprio, ioprio_class;
 240         /* next ioprio and ioprio class if a change is in progress */
 241         unsigned short new_ioprio, new_ioprio_class;
 242
 243         /*
 244          * Shared bfq_queue if queue is cooperating with one or more
 245          * other queues.
 246          */
 247         struct bfq_queue *new_bfqq;
 248         /* request-position tree member (see bfq_group's @rq_pos_tree) */
 249         struct rb_node pos_node;
 250         /* request-position tree root (see bfq_group's @rq_pos_tree) */
 251         struct rb_root *pos_root;
 252
 253         /* sorted list of pending requests */
 254         struct rb_root sort_list;
 255         /* if fifo isn't expired, next request to serve */
 256         struct request *next_rq;
 257         /* number of sync and async requests queued */
 258         int queued[2];
 259         /* number of requests currently allocated */
 260         int allocated;
 261         /* number of pending metadata requests */
 262         int meta_pending;
 263         /* fifo list of requests in sort_list */
 264         struct list_head fifo;
 265
 266         /* entity representing this queue in the scheduler */
 267         struct bfq_entity entity;
 268
 269         /* maximum budget allowed from the feedback mechanism */
 270         int max_budget;
 271         /* budget expiration (in jiffies) */
 272         unsigned long budget_timeout;
 273
 274         /* number of requests on the dispatch list or inside driver */
 275         int dispatched;
 276
 277         /* status flags */
 278         unsigned long flags;
 279
 280         /* node for active/idle bfqq list inside parent bfqd */
 281         struct list_head bfqq_list;
 282
 283         /* associated @bfq_ttime struct */
 284         struct bfq_ttime ttime;
 285
 286         /* bit vector: a 1 for each seeky requests in history */
 287         u32 seek_history;
 288
 289         /* node for the device's burst list */
 290         struct hlist_node burst_list_node;
 291
 292         /* position of the last request enqueued */
 293         sector_t last_request_pos;
 294
 295         /* Number of consecutive pairs of request completion and
 296          * arrival, such that the queue becomes idle after the
 297          * completion, but the next request arrives within an idle
 298          * time slice; used only if the queue's IO_bound flag has been
 299          * cleared.
 300          */
 301         unsigned int requests_within_timer;
 302
 303         /* pid of the process owning the queue, used for logging purposes */
 304         pid_t pid;
 305
 306         /*
 307          * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL
 308          * if the queue is shared.
 309          */
 310         struct bfq_io_cq *bic;
 311
 312         /* current maximum weight-raising time for this queue */
 313         unsigned long wr_cur_max_time;
 314         /*
 315          * Minimum time instant such that, only if a new request is
 316          * enqueued after this time instant in an idle @bfq_queue with
 317          * no outstanding requests, then the task associated with the
 318          * queue it is deemed as soft real-time (see the comments on
 319          * the function bfq_bfqq_softrt_next_start())
 320          */
 321         unsigned long soft_rt_next_start;
 322         /*
 323          * Start time of the current weight-raising period if
 324          * the @bfq-queue is being weight-raised, otherwise
 325          * finish time of the last weight-raising period.
 326          */
 327         unsigned long last_wr_start_finish;
 328         /* factor by which the weight of this queue is multiplied */
 329         unsigned int wr_coeff;
 330         /*
 331          * Time of the last transition of the @bfq_queue from idle to
 332          * backlogged.
 333          */
 334         unsigned long last_idle_bklogged;
 335         /*
 336          * Cumulative service received from the @bfq_queue since the
 337          * last transition from idle to backlogged.
 338          */
 339         unsigned long service_from_backlogged;
 340         /*
 341          * Cumulative service received from the @bfq_queue since its
 342          * last transition to weight-raised state.
 343          */
 344         unsigned long service_from_wr;
 345
 346         /*
 347          * Value of wr start time when switching to soft rt
 348          */
 349         unsigned long wr_start_at_switch_to_srt;
 350
 351         unsigned long split_time; /* time of last split */
 352
 353         unsigned long first_IO_time; /* time of first I/O for this queue */
 354
 355         /* max service rate measured so far */
 356         u32 max_service_rate;
 357         /*
 358          * Ratio between the service received by bfqq while it is in
 359          * service, and the cumulative service (of requests of other
 360          * queues) that may be injected while bfqq is empty but still
 361          * in service. To increase precision, the coefficient is
 362          * measured in tenths of unit. Here are some example of (1)
 363          * ratios, (2) resulting percentages of service injected
 364          * w.r.t. to the total service dispatched while bfqq is in
 365          * service, and (3) corresponding values of the coefficient:
 366          * 1 (50%) -> 10
 367          * 2 (33%) -> 20
 368          * 10 (9%) -> 100
 369          * 9.9 (9%) -> 99
 370          * 1.5 (40%) -> 15
 371          * 0.5 (66%) -> 5
 372          * 0.1 (90%) -> 1
 373          *
 374          * So, if the coefficient is lower than 10, then
 375          * injected service is more than bfqq service.
 376          */
 377         unsigned int inject_coeff;
 378         /* amount of service injected in current service slot */
 379         unsigned int injected_service;
 380 };
 381
 382 /**
 383  * struct bfq_io_cq - per (request_queue, io_context) structure.
 384  */
 385 struct bfq_io_cq {
 386         /* associated io_cq structure */
 387         struct io_cq icq; /* must be the first member */
 388         /* array of two process queues, the sync and the async */
 389         struct bfq_queue *bfqq[2];
 390         /* per (request_queue, blkcg) ioprio */
 391         int ioprio;
 392 #ifdef CONFIG_BFQ_GROUP_IOSCHED
 393         uint64_t blkcg_serial_nr; /* the current blkcg serial */
 394 #endif
 395         /*
 396          * Snapshot of the has_short_time flag before merging; taken
 397          * to remember its value while the queue is merged, so as to
 398          * be able to restore it in case of split.
 399          */
 400         bool saved_has_short_ttime;
 401         /*
 402          * Same purpose as the previous two fields for the I/O bound
 403          * classification of a queue.
 404          */
 405         bool saved_IO_bound;
 406
 407         /*
 408          * Same purpose as the previous fields for the value of the
 409          * field keeping the queue's belonging to a large burst
 410          */
 411         bool saved_in_large_burst;
 412         /*
 413          * True if the queue belonged to a burst list before its merge
 414          * with another cooperating queue.
 415          */
 416         bool was_in_burst_list;
 417
 418         /*
 419          * Similar to previous fields: save wr information.
 420          */
 421         unsigned long saved_wr_coeff;
 422         unsigned long saved_last_wr_start_finish;
 423         unsigned long saved_wr_start_at_switch_to_srt;
 424         unsigned int saved_wr_cur_max_time;
 425         struct bfq_ttime saved_ttime;
 426 };
 427
 428 /**
 429  * struct bfq_data - per-device data structure.
 430  *
 431  * All the fields are protected by @lock.
 432  */
 433 struct bfq_data {
 434         /* device request queue */
 435         struct request_queue *queue;
 436         /* dispatch queue */
 437         struct list_head dispatch;
 438
 439         /* root bfq_group for the device */
 440         struct bfq_group *root_group;
 441
 442         /*
 443          * rbtree of weight counters of @bfq_queues, sorted by
 444          * weight. Used to keep track of whether all @bfq_queues have
 445          * the same weight. The tree contains one counter for each
 446          * distinct weight associated to some active and not
 447          * weight-raised @bfq_queue (see the comments to the functions
 448          * bfq_weights_tree_[add|remove] for further details).
 449          */
 450         struct rb_root queue_weights_tree;
 451         /*
 452          * rbtree of non-queue @bfq_entity weight counters, sorted by
 453          * weight. Used to keep track of whether all @bfq_groups have
 454          * the same weight. The tree contains one counter for each
 455          * distinct weight associated to some active @bfq_group (see
 456          * the comments to the functions bfq_weights_tree_[add|remove]
 457          * for further details).
 458          */
 459         struct rb_root group_weights_tree;
 460
 461         /*
 462          * Number of bfq_queues containing requests (including the
 463          * queue in service, even if it is idling).
 464          */
 465         int busy_queues;
 466         /* number of weight-raised busy @bfq_queues */
 467         int wr_busy_queues;
 468         /* number of queued requests */
 469         int queued;
 470         /* number of requests dispatched and waiting for completion */
 471         int rq_in_driver;
 472
 473         /*
 474          * Maximum number of requests in driver in the last
 475          * @hw_tag_samples completed requests.
 476          */
 477         int max_rq_in_driver;
 478         /* number of samples used to calculate hw_tag */
 479         int hw_tag_samples;
 480         /* flag set to one if the driver is showing a queueing behavior */
 481         int hw_tag;
 482
 483         /* number of budgets assigned */
 484         int budgets_assigned;
 485
 486         /*
 487          * Timer set when idling (waiting) for the next request from
 488          * the queue in service.
 489          */
 490         struct hrtimer idle_slice_timer;
 491
 492         /* bfq_queue in service */
 493         struct bfq_queue *in_service_queue;
 494
 495         /* on-disk position of the last served request */
 496         sector_t last_position;
 497
 498         /* position of the last served request for the in-service queue */
 499         sector_t in_serv_last_pos;
 500
 501         /* time of last request completion (ns) */
 502         u64 last_completion;
 503
 504         /* time of first rq dispatch in current observation interval (ns) */
 505         u64 first_dispatch;
 506         /* time of last rq dispatch in current observation interval (ns) */
 507         u64 last_dispatch;
 508
 509         /* beginning of the last budget */
 510         ktime_t last_budget_start;
 511         /* beginning of the last idle slice */
 512         ktime_t last_idling_start;
 513
 514         /* number of samples in current observation interval */
 515         int peak_rate_samples;
 516         /* num of samples of seq dispatches in current observation interval */
 517         u32 sequential_samples;
 518         /* total num of sectors transferred in current observation interval */
 519         u64 tot_sectors_dispatched;
 520         /* max rq size seen during current observation interval (sectors) */
 521         u32 last_rq_max_size;
 522         /* time elapsed from first dispatch in current observ. interval (us) */
 523         u64 delta_from_first;
 524         /*
 525          * Current estimate of the device peak rate, measured in
 526          * [(sectors/usec) / 2^BFQ_RATE_SHIFT]. The left-shift by
 527          * BFQ_RATE_SHIFT is performed to increase precision in
 528          * fixed-point calculations.
 529          */
 530         u32 peak_rate;
 531
 532         /* maximum budget allotted to a bfq_queue before rescheduling */
 533         int bfq_max_budget;
 534
 535         /* list of all the bfq_queues active on the device */
 536         struct list_head active_list;
 537         /* list of all the bfq_queues idle on the device */
 538         struct list_head idle_list;
 539
 540         /*
 541          * Timeout for async/sync requests; when it fires, requests
 542          * are served in fifo order.
 543          */
 544         u64 bfq_fifo_expire[2];
 545         /* weight of backward seeks wrt forward ones */
 546         unsigned int bfq_back_penalty;
 547         /* maximum allowed backward seek */
 548         unsigned int bfq_back_max;
 549         /* maximum idling time */
 550         u32 bfq_slice_idle;
 551
 552         /* user-configured max budget value (0 for auto-tuning) */
 553         int bfq_user_max_budget;
 554         /*
 555          * Timeout for bfq_queues to consume their budget; used to
 556          * prevent seeky queues from imposing long latencies to
 557          * sequential or quasi-sequential ones (this also implies that
 558          * seeky queues cannot receive guarantees in the service
 559          * domain; after a timeout they are charged for the time they
 560          * have been in service, to preserve fairness among them, but
 561          * without service-domain guarantees).
 562          */
 563         unsigned int bfq_timeout;
 564
 565         /*
 566          * Number of consecutive requests that must be issued within
 567          * the idle time slice to set again idling to a queue which
 568          * was marked as non-I/O-bound (see the definition of the
 569          * IO_bound flag for further details).
 570          */
 571         unsigned int bfq_requests_within_timer;
 572
 573         /*
 574          * Force device idling whenever needed to provide accurate
 575          * service guarantees, without caring about throughput
 576          * issues. CAVEAT: this may even increase latencies, in case
 577          * of useless idling for processes that did stop doing I/O.
 578          */
 579         bool strict_guarantees;
 580
 581         /*
 582          * Last time at which a queue entered the current burst of
 583          * queues being activated shortly after each other; for more
 584          * details about this and the following parameters related to
 585          * a burst of activations, see the comments on the function
 586          * bfq_handle_burst.
 587          */
 588         unsigned long last_ins_in_burst;
 589         /*
 590          * Reference time interval used to decide whether a queue has
 591          * been activated shortly after @last_ins_in_burst.
 592          */
 593         unsigned long bfq_burst_interval;
 594         /* number of queues in the current burst of queue activations */
 595         int burst_size;
 596
 597         /* common parent entity for the queues in the burst */
 598         struct bfq_entity *burst_parent_entity;
 599         /* Maximum burst size above which the current queue-activation
 600          * burst is deemed as 'large'.
 601          */
 602         unsigned long bfq_large_burst_thresh;
 603         /* true if a large queue-activation burst is in progress */
 604         bool large_burst;
 605         /*
 606          * Head of the burst list (as for the above fields, more
 607          * details in the comments on the function bfq_handle_burst).
 608          */
 609         struct hlist_head burst_list;
 610
 611         /* if set to true, low-latency heuristics are enabled */
 612         bool low_latency;
 613         /*
 614          * Maximum factor by which the weight of a weight-raised queue
 615          * is multiplied.
 616          */
 617         unsigned int bfq_wr_coeff;
 618         /* maximum duration of a weight-raising period (jiffies) */
 619         unsigned int bfq_wr_max_time;
 620
 621         /* Maximum weight-raising duration for soft real-time processes */
 622         unsigned int bfq_wr_rt_max_time;
 623         /*
 624          * Minimum idle period after which weight-raising may be
 625          * reactivated for a queue (in jiffies).
 626          */
 627         unsigned int bfq_wr_min_idle_time;
 628         /*
 629          * Minimum period between request arrivals after which
 630          * weight-raising may be reactivated for an already busy async
 631          * queue (in jiffies).
 632          */
 633         unsigned long bfq_wr_min_inter_arr_async;
 634
 635         /* Max service-rate for a soft real-time queue, in sectors/sec */
 636         unsigned int bfq_wr_max_softrt_rate;
 637         /*
 638          * Cached value of the product ref_rate*ref_wr_duration, used
 639          * for computing the maximum duration of weight raising
 640          * automatically.
 641          */
 642         u64 rate_dur_prod;
 643
 644         /* fallback dummy bfqq for extreme OOM conditions */
 645         struct bfq_queue oom_bfqq;
 646
 647         spinlock_t lock;
 648
 649         /*
 650          * bic associated with the task issuing current bio for
 651          * merging. This and the next field are used as a support to
 652          * be able to perform the bic lookup, needed by bio-merge
 653          * functions, before the scheduler lock is taken, and thus
 654          * avoid taking the request-queue lock while the scheduler
 655          * lock is being held.
 656          */
 657         struct bfq_io_cq *bio_bic;
 658         /* bfqq associated with the task issuing current bio for merging */
 659         struct bfq_queue *bio_bfqq;
 660
 661         /*
 662          * Depth limits used in bfq_limit_depth (see comments on the
 663          * function)
 664          */
 665         unsigned int word_depths[2][2];
 666 };
 667
 668 enum bfqq_state_flags {
 669         BFQQF_just_created = 0, /* queue just allocated */
 670         BFQQF_busy,             /* has requests or is in service */
 671         BFQQF_wait_request,     /* waiting for a request */
 672         BFQQF_non_blocking_wait_rq, /*
 673                                      * waiting for a request
 674                                      * without idling the device
 675                                      */
 676         BFQQF_fifo_expire,      /* FIFO checked in this slice */
 677         BFQQF_has_short_ttime,  /* queue has a short think time */
 678         BFQQF_sync,             /* synchronous queue */
 679         BFQQF_IO_bound,         /*
 680                                  * bfqq has timed-out at least once
 681                                  * having consumed at most 2/10 of
 682                                  * its budget
 683                                  */
 684         BFQQF_in_large_burst,   /*
 685                                  * bfqq activated in a large burst,
 686                                  * see comments to bfq_handle_burst.
 687                                  */
 688         BFQQF_softrt_update,    /*
 689                                  * may need softrt-next-start
 690                                  * update
 691                                  */
 692         BFQQF_coop,             /* bfqq is shared */
 693         BFQQF_split_coop        /* shared bfqq will be split */
 694 };
 695
 696 #define BFQ_BFQQ_FNS(name)                                              \
 697 void bfq_mark_bfqq_##name(struct bfq_queue *bfqq);                      \
 698 void bfq_clear_bfqq_##name(struct bfq_queue *bfqq);                     \
 699 int bfq_bfqq_##name(const struct bfq_queue *bfqq);
 700
 701 BFQ_BFQQ_FNS(just_created);
 702 BFQ_BFQQ_FNS(busy);
 703 BFQ_BFQQ_FNS(wait_request);
 704 BFQ_BFQQ_FNS(non_blocking_wait_rq);
 705 BFQ_BFQQ_FNS(fifo_expire);
 706 BFQ_BFQQ_FNS(has_short_ttime);
 707 BFQ_BFQQ_FNS(sync);
 708 BFQ_BFQQ_FNS(IO_bound);
 709 BFQ_BFQQ_FNS(in_large_burst);
 710 BFQ_BFQQ_FNS(coop);
 711 BFQ_BFQQ_FNS(split_coop);
 712 BFQ_BFQQ_FNS(softrt_update);
 713 #undef BFQ_BFQQ_FNS
 714
 715 /* Expiration reasons. */
 716 enum bfqq_expiration {
 717         BFQQE_TOO_IDLE = 0,             /*
 718                                          * queue has been idling for
 719                                          * too long
 720                                          */
 721         BFQQE_BUDGET_TIMEOUT,   /* budget took too long to be used */
 722         BFQQE_BUDGET_EXHAUSTED, /* budget consumed */
 723         BFQQE_NO_MORE_REQUESTS, /* the queue has no more requests */
 724         BFQQE_PREEMPTED         /* preemption in progress */
 725 };
 726
 727 struct bfqg_stats {
 728 #if defined(CONFIG_BFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
 729         /* number of ios merged */
 730         struct blkg_rwstat              merged;
 731         /* total time spent on device in ns, may not be accurate w/ queueing */
 732         struct blkg_rwstat              service_time;
 733         /* total time spent waiting in scheduler queue in ns */
 734         struct blkg_rwstat              wait_time;
 735         /* number of IOs queued up */
 736         struct blkg_rwstat              queued;
 737         /* total disk time and nr sectors dispatched by this group */
 738         struct blkg_stat                time;
 739         /* sum of number of ios queued across all samples */
 740         struct blkg_stat                avg_queue_size_sum;
 741         /* count of samples taken for average */
 742         struct blkg_stat                avg_queue_size_samples;
 743         /* how many times this group has been removed from service tree */
 744         struct blkg_stat                dequeue;
 745         /* total time spent waiting for it to be assigned a timeslice. */
 746         struct blkg_stat                group_wait_time;
 747         /* time spent idling for this blkcg_gq */
 748         struct blkg_stat                idle_time;
 749         /* total time with empty current active q with other requests queued */
 750         struct blkg_stat                empty_time;
 751         /* fields after this shouldn't be cleared on stat reset */
 752         u64                             start_group_wait_time;
 753         u64                             start_idle_time;
 754         u64                             start_empty_time;
 755         uint16_t                        flags;
 756 #endif  /* CONFIG_BFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
 757 };
 758
 759 #ifdef CONFIG_BFQ_GROUP_IOSCHED
 760
 761 /*
 762  * struct bfq_group_data - per-blkcg storage for the blkio subsystem.
 763  *
 764  * @ps: @blkcg_policy_storage that this structure inherits
 765  * @weight: weight of the bfq_group
 766  */
 767 struct bfq_group_data {
 768         /* must be the first member */
 769         struct blkcg_policy_data pd;
 770
 771         unsigned int weight;
 772 };
 773
 774 /**
 775  * struct bfq_group - per (device, cgroup) data structure.
 776  * @entity: schedulable entity to insert into the parent group sched_data.
 777  * @sched_data: own sched_data, to contain child entities (they may be
 778  *              both bfq_queues and bfq_groups).
 779  * @bfqd: the bfq_data for the device this group acts upon.
 780  * @async_bfqq: array of async queues for all the tasks belonging to
 781  *              the group, one queue per ioprio value per ioprio_class,
 782  *              except for the idle class that has only one queue.
 783  * @async_idle_bfqq: async queue for the idle class (ioprio is ignored).
 784  * @my_entity: pointer to @entity, %NULL for the toplevel group; used
 785  *             to avoid too many special cases during group creation/
 786  *             migration.
 787  * @stats: stats for this bfqg.
 788  * @active_entities: number of active entities belonging to the group;
 789  *                   unused for the root group. Used to know whether there
 790  *                   are groups with more than one active @bfq_entity
 791  *                   (see the comments to the function
 792  *                   bfq_bfqq_may_idle()).
 793  * @rq_pos_tree: rbtree sorted by next_request position, used when
 794  *               determining if two or more queues have interleaving
 795  *               requests (see bfq_find_close_cooperator()).
 796  *
 797  * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup
 798  * there is a set of bfq_groups, each one collecting the lower-level
 799  * entities belonging to the group that are acting on the same device.
 800  *
 801  * Locking works as follows:
 802  *    o @bfqd is protected by the queue lock, RCU is used to access it
 803  *      from the readers.
 804  *    o All the other fields are protected by the @bfqd queue lock.
 805  */
 806 struct bfq_group {
 807         /* must be the first member */
 808         struct blkg_policy_data pd;
 809
 810         /* cached path for this blkg (see comments in bfq_bic_update_cgroup) */
 811         char blkg_path[128];
 812
 813         /* reference counter (see comments in bfq_bic_update_cgroup) */
 814         int ref;
 815
 816         struct bfq_entity entity;
 817         struct bfq_sched_data sched_data;
 818
 819         void *bfqd;
 820
 821         struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
 822         struct bfq_queue *async_idle_bfqq;
 823
 824         struct bfq_entity *my_entity;
 825
 826         int active_entities;
 827
 828         struct rb_root rq_pos_tree;
 829
 830         struct bfqg_stats stats;
 831 };
 832
 833 #else
 834 struct bfq_group {
 835         struct bfq_sched_data sched_data;
 836
 837         struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
 838         struct bfq_queue *async_idle_bfqq;
 839
 840         struct rb_root rq_pos_tree;
 841 };
 842 #endif
 843
 844 struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
 845
 846 /* --------------- main algorithm interface ----------------- */
 847
 848 #define BFQ_SERVICE_TREE_INIT   ((struct bfq_service_tree)              \
 849                                 { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
 850
 851 extern const int bfq_timeout;
 852
 853 struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync);
 854 void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, bool is_sync);
 855 struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic);
 856 void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq);
 857 void bfq_weights_tree_add(struct bfq_data *bfqd, struct bfq_entity *entity,
 858                           struct rb_root *root);
 859 void __bfq_weights_tree_remove(struct bfq_data *bfqd,
 860                                struct bfq_entity *entity,
 861                                struct rb_root *root);
 862 void bfq_weights_tree_remove(struct bfq_data *bfqd,
 863                              struct bfq_queue *bfqq);
 864 void bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 865                      bool compensate, enum bfqq_expiration reason);
 866 void bfq_put_queue(struct bfq_queue *bfqq);
 867 void bfq_end_wr_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
 868 void bfq_schedule_dispatch(struct bfq_data *bfqd);
 869 void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
 870
 871 /* ------------ end of main algorithm interface -------------- */
 872
 873 /* ---------------- cgroups-support interface ---------------- */
 874
 875 void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
 876                               unsigned int op);
 877 void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op);
 878 void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op);
 879 void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns,
 880                                   u64 io_start_time_ns, unsigned int op);
 881 void bfqg_stats_update_dequeue(struct bfq_group *bfqg);
 882 void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg);
 883 void bfqg_stats_update_idle_time(struct bfq_group *bfqg);
 884 void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg);
 885 void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg);
 886 void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 887                    struct bfq_group *bfqg);
 888
 889 void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg);
 890 void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio);
 891 void bfq_end_wr_async(struct bfq_data *bfqd);
 892 struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
 893                                      struct blkcg *blkcg);
 894 struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
 895 struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
 896 struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node);
 897 void bfqg_and_blkg_put(struct bfq_group *bfqg);
 898
 899 #ifdef CONFIG_BFQ_GROUP_IOSCHED
 900 extern struct cftype bfq_blkcg_legacy_files[];
 901 extern struct cftype bfq_blkg_files[];
 902 extern struct blkcg_policy blkcg_policy_bfq;
 903 #endif
 904
 905 /* ------------- end of cgroups-support interface ------------- */
 906
 907 /* - interface of the internal hierarchical B-WF2Q+ scheduler - */
 908
 909 #ifdef CONFIG_BFQ_GROUP_IOSCHED
 910 /* both next loops stop at one of the child entities of the root group */
 911 #define for_each_entity(entity) \
 912         for (; entity ; entity = entity->parent)
 913
 914 /*
 915  * For each iteration, compute parent in advance, so as to be safe if
 916  * entity is deallocated during the iteration. Such a deallocation may
 917  * happen as a consequence of a bfq_put_queue that frees the bfq_queue
 918  * containing entity.
 919  */
 920 #define for_each_entity_safe(entity, parent) \
 921         for (; entity && ({ parent = entity->parent; 1; }); entity = parent)
 922
 923 #else /* CONFIG_BFQ_GROUP_IOSCHED */
 924 /*
 925  * Next two macros are fake loops when cgroups support is not
 926  * enabled. I fact, in such a case, there is only one level to go up
 927  * (to reach the root group).
 928  */
 929 #define for_each_entity(entity) \
 930         for (; entity ; entity = NULL)
 931
 932 #define for_each_entity_safe(entity, parent) \
 933         for (parent = NULL; entity ; entity = parent)
 934 #endif /* CONFIG_BFQ_GROUP_IOSCHED */
 935
 936 struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq);
 937 struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
 938 struct bfq_service_tree *bfq_entity_service_tree(struct bfq_entity *entity);
 939 struct bfq_entity *bfq_entity_of(struct rb_node *node);
 940 unsigned short bfq_ioprio_to_weight(int ioprio);
 941 void bfq_put_idle_entity(struct bfq_service_tree *st,
 942                          struct bfq_entity *entity);
 943 struct bfq_service_tree *
 944 __bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
 945                                 struct bfq_entity *entity,
 946                                 bool update_class_too);
 947 void bfq_bfqq_served(struct bfq_queue *bfqq, int served);
 948 void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 949                           unsigned long time_ms);
 950 bool __bfq_deactivate_entity(struct bfq_entity *entity,
 951                              bool ins_into_idle_tree);
 952 bool next_queue_may_preempt(struct bfq_data *bfqd);
 953 struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd);
 954 void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd);
 955 void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 956                          bool ins_into_idle_tree, bool expiration);
 957 void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
 958 void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 959                       bool expiration);
 960 void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 961                        bool expiration);
 962 void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq);
 963
 964 /* --------------- end of interface of B-WF2Q+ ---------------- */
 965
 966 /* Logging facilities. */
 967 #ifdef CONFIG_BFQ_GROUP_IOSCHED
 968 struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
 969
 970 #define bfq_log_bfqq(bfqd, bfqq, fmt, args...)  do {                    \
 971         blk_add_cgroup_trace_msg((bfqd)->queue,                         \
 972                         bfqg_to_blkg(bfqq_group(bfqq))->blkcg,          \
 973                         "bfq%d%c " fmt, (bfqq)->pid,                    \
 974                         bfq_bfqq_sync((bfqq)) ? 'S' : 'A', ##args);     \
 975 } while (0)
 976
 977 #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)  do {                    \
 978         blk_add_cgroup_trace_msg((bfqd)->queue,                         \
 979                 bfqg_to_blkg(bfqg)->blkcg, fmt, ##args);                \
 980 } while (0)
 981
 982 #else /* CONFIG_BFQ_GROUP_IOSCHED */
 983
 984 #define bfq_log_bfqq(bfqd, bfqq, fmt, args...)  \
 985         blk_add_trace_msg((bfqd)->queue, "bfq%d%c " fmt, (bfqq)->pid,   \
 986                         bfq_bfqq_sync((bfqq)) ? 'S' : 'A',              \
 987                                 ##args)
 988 #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)          do {} while (0)
 989
 990 #endif /* CONFIG_BFQ_GROUP_IOSCHED */
 991
 992 #define bfq_log(bfqd, fmt, args...) \
 993         blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
 994
 995 #endif /* _BFQ_H */