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 queues
 112  *                             with a given weight.
 113  */
 114 struct bfq_weight_counter {
 115         unsigned int weight; /* weight of the queues this counter refers to */
 116         unsigned int num_active; /* nr of active queues with this weight */
 117         /*
 118          * Weights tree member (see bfq_data's @queue_weights_tree)
 119          */
 120         struct rb_node weights_node;
 121 };
 122
 123 /**
 124  * struct bfq_entity - schedulable entity.
 125  *
 126  * A bfq_entity is used to represent either a bfq_queue (leaf node in the
 127  * cgroup hierarchy) or a bfq_group into the upper level scheduler.  Each
 128  * entity belongs to the sched_data of the parent group in the cgroup
 129  * hierarchy.  Non-leaf entities have also their own sched_data, stored
 130  * in @my_sched_data.
 131  *
 132  * Each entity stores independently its priority values; this would
 133  * allow different weights on different devices, but this
 134  * functionality is not exported to userspace by now.  Priorities and
 135  * weights are updated lazily, first storing the new values into the
 136  * new_* fields, then setting the @prio_changed flag.  As soon as
 137  * there is a transition in the entity state that allows the priority
 138  * update to take place the effective and the requested priority
 139  * values are synchronized.
 140  *
 141  * Unless cgroups are used, the weight value is calculated from the
 142  * ioprio to export the same interface as CFQ.  When dealing with
 143  * ``well-behaved'' queues (i.e., queues that do not spend too much
 144  * time to consume their budget and have true sequential behavior, and
 145  * when there are no external factors breaking anticipation) the
 146  * relative weights at each level of the cgroups hierarchy should be
 147  * guaranteed.  All the fields are protected by the queue lock of the
 148  * containing bfqd.
 149  */
 150 struct bfq_entity {
 151         /* service_tree member */
 152         struct rb_node rb_node;
 153
 154         /*
 155          * Flag, true if the entity is on a tree (either the active or
 156          * the idle one of its service_tree) or is in service.
 157          */
 158         bool on_st;
 159
 160         /* B-WF2Q+ start and finish timestamps [sectors/weight] */
 161         u64 start, finish;
 162
 163         /* tree the entity is enqueued into; %NULL if not on a tree */
 164         struct rb_root *tree;
 165
 166         /*
 167          * minimum start time of the (active) subtree rooted at this
 168          * entity; used for O(log N) lookups into active trees
 169          */
 170         u64 min_start;
 171
 172         /* amount of service received during the last service slot */
 173         int service;
 174
 175         /* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */
 176         int budget;
 177
 178         /* weight of the queue */
 179         int weight;
 180         /* next weight if a change is in progress */
 181         int new_weight;
 182
 183         /* original weight, used to implement weight boosting */
 184         int orig_weight;
 185
 186         /* parent entity, for hierarchical scheduling */
 187         struct bfq_entity *parent;
 188
 189         /*
 190          * For non-leaf nodes in the hierarchy, the associated
 191          * scheduler queue, %NULL on leaf nodes.
 192          */
 193         struct bfq_sched_data *my_sched_data;
 194         /* the scheduler queue this entity belongs to */
 195         struct bfq_sched_data *sched_data;
 196
 197         /* flag, set to request a weight, ioprio or ioprio_class change  */
 198         int prio_changed;
 199 };
 200
 201 struct bfq_group;
 202
 203 /**
 204  * struct bfq_ttime - per process thinktime stats.
 205  */
 206 struct bfq_ttime {
 207         /* completion time of the last request */
 208         u64 last_end_request;
 209
 210         /* total process thinktime */
 211         u64 ttime_total;
 212         /* number of thinktime samples */
 213         unsigned long ttime_samples;
 214         /* average process thinktime */
 215         u64 ttime_mean;
 216 };
 217
 218 /**
 219  * struct bfq_queue - leaf schedulable entity.
 220  *
 221  * A bfq_queue is a leaf request queue; it can be associated with an
 222  * io_context or more, if it  is  async or shared  between  cooperating
 223  * processes. @cgroup holds a reference to the cgroup, to be sure that it
 224  * does not disappear while a bfqq still references it (mostly to avoid
 225  * races between request issuing and task migration followed by cgroup
 226  * destruction).
 227  * All the fields are protected by the queue lock of the containing bfqd.
 228  */
 229 struct bfq_queue {
 230         /* reference counter */
 231         int ref;
 232         /* parent bfq_data */
 233         struct bfq_data *bfqd;
 234
 235         /* current ioprio and ioprio class */
 236         unsigned short ioprio, ioprio_class;
 237         /* next ioprio and ioprio class if a change is in progress */
 238         unsigned short new_ioprio, new_ioprio_class;
 239
 240         /*
 241          * Shared bfq_queue if queue is cooperating with one or more
 242          * other queues.
 243          */
 244         struct bfq_queue *new_bfqq;
 245         /* request-position tree member (see bfq_group's @rq_pos_tree) */
 246         struct rb_node pos_node;
 247         /* request-position tree root (see bfq_group's @rq_pos_tree) */
 248         struct rb_root *pos_root;
 249
 250         /* sorted list of pending requests */
 251         struct rb_root sort_list;
 252         /* if fifo isn't expired, next request to serve */
 253         struct request *next_rq;
 254         /* number of sync and async requests queued */
 255         int queued[2];
 256         /* number of requests currently allocated */
 257         int allocated;
 258         /* number of pending metadata requests */
 259         int meta_pending;
 260         /* fifo list of requests in sort_list */
 261         struct list_head fifo;
 262
 263         /* entity representing this queue in the scheduler */
 264         struct bfq_entity entity;
 265
 266         /* pointer to the weight counter associated with this entity */
 267         struct bfq_weight_counter *weight_counter;
 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          * number of groups with requests still waiting for completion
 453          */
 454         unsigned int num_active_groups;
 455
 456         /*
 457          * Number of bfq_queues containing requests (including the
 458          * queue in service, even if it is idling).
 459          */
 460         int busy_queues;
 461         /* number of weight-raised busy @bfq_queues */
 462         int wr_busy_queues;
 463         /* number of queued requests */
 464         int queued;
 465         /* number of requests dispatched and waiting for completion */
 466         int rq_in_driver;
 467
 468         /*
 469          * Maximum number of requests in driver in the last
 470          * @hw_tag_samples completed requests.
 471          */
 472         int max_rq_in_driver;
 473         /* number of samples used to calculate hw_tag */
 474         int hw_tag_samples;
 475         /* flag set to one if the driver is showing a queueing behavior */
 476         int hw_tag;
 477
 478         /* number of budgets assigned */
 479         int budgets_assigned;
 480
 481         /*
 482          * Timer set when idling (waiting) for the next request from
 483          * the queue in service.
 484          */
 485         struct hrtimer idle_slice_timer;
 486
 487         /* bfq_queue in service */
 488         struct bfq_queue *in_service_queue;
 489
 490         /* on-disk position of the last served request */
 491         sector_t last_position;
 492
 493         /* time of last request completion (ns) */
 494         u64 last_completion;
 495
 496         /* time of first rq dispatch in current observation interval (ns) */
 497         u64 first_dispatch;
 498         /* time of last rq dispatch in current observation interval (ns) */
 499         u64 last_dispatch;
 500
 501         /* beginning of the last budget */
 502         ktime_t last_budget_start;
 503         /* beginning of the last idle slice */
 504         ktime_t last_idling_start;
 505
 506         /* number of samples in current observation interval */
 507         int peak_rate_samples;
 508         /* num of samples of seq dispatches in current observation interval */
 509         u32 sequential_samples;
 510         /* total num of sectors transferred in current observation interval */
 511         u64 tot_sectors_dispatched;
 512         /* max rq size seen during current observation interval (sectors) */
 513         u32 last_rq_max_size;
 514         /* time elapsed from first dispatch in current observ. interval (us) */
 515         u64 delta_from_first;
 516         /*
 517          * Current estimate of the device peak rate, measured in
 518          * [(sectors/usec) / 2^BFQ_RATE_SHIFT]. The left-shift by
 519          * BFQ_RATE_SHIFT is performed to increase precision in
 520          * fixed-point calculations.
 521          */
 522         u32 peak_rate;
 523
 524         /* maximum budget allotted to a bfq_queue before rescheduling */
 525         int bfq_max_budget;
 526
 527         /* list of all the bfq_queues active on the device */
 528         struct list_head active_list;
 529         /* list of all the bfq_queues idle on the device */
 530         struct list_head idle_list;
 531
 532         /*
 533          * Timeout for async/sync requests; when it fires, requests
 534          * are served in fifo order.
 535          */
 536         u64 bfq_fifo_expire[2];
 537         /* weight of backward seeks wrt forward ones */
 538         unsigned int bfq_back_penalty;
 539         /* maximum allowed backward seek */
 540         unsigned int bfq_back_max;
 541         /* maximum idling time */
 542         u32 bfq_slice_idle;
 543
 544         /* user-configured max budget value (0 for auto-tuning) */
 545         int bfq_user_max_budget;
 546         /*
 547          * Timeout for bfq_queues to consume their budget; used to
 548          * prevent seeky queues from imposing long latencies to
 549          * sequential or quasi-sequential ones (this also implies that
 550          * seeky queues cannot receive guarantees in the service
 551          * domain; after a timeout they are charged for the time they
 552          * have been in service, to preserve fairness among them, but
 553          * without service-domain guarantees).
 554          */
 555         unsigned int bfq_timeout;
 556
 557         /*
 558          * Number of consecutive requests that must be issued within
 559          * the idle time slice to set again idling to a queue which
 560          * was marked as non-I/O-bound (see the definition of the
 561          * IO_bound flag for further details).
 562          */
 563         unsigned int bfq_requests_within_timer;
 564
 565         /*
 566          * Force device idling whenever needed to provide accurate
 567          * service guarantees, without caring about throughput
 568          * issues. CAVEAT: this may even increase latencies, in case
 569          * of useless idling for processes that did stop doing I/O.
 570          */
 571         bool strict_guarantees;
 572
 573         /*
 574          * Last time at which a queue entered the current burst of
 575          * queues being activated shortly after each other; for more
 576          * details about this and the following parameters related to
 577          * a burst of activations, see the comments on the function
 578          * bfq_handle_burst.
 579          */
 580         unsigned long last_ins_in_burst;
 581         /*
 582          * Reference time interval used to decide whether a queue has
 583          * been activated shortly after @last_ins_in_burst.
 584          */
 585         unsigned long bfq_burst_interval;
 586         /* number of queues in the current burst of queue activations */
 587         int burst_size;
 588
 589         /* common parent entity for the queues in the burst */
 590         struct bfq_entity *burst_parent_entity;
 591         /* Maximum burst size above which the current queue-activation
 592          * burst is deemed as 'large'.
 593          */
 594         unsigned long bfq_large_burst_thresh;
 595         /* true if a large queue-activation burst is in progress */
 596         bool large_burst;
 597         /*
 598          * Head of the burst list (as for the above fields, more
 599          * details in the comments on the function bfq_handle_burst).
 600          */
 601         struct hlist_head burst_list;
 602
 603         /* if set to true, low-latency heuristics are enabled */
 604         bool low_latency;
 605         /*
 606          * Maximum factor by which the weight of a weight-raised queue
 607          * is multiplied.
 608          */
 609         unsigned int bfq_wr_coeff;
 610         /* maximum duration of a weight-raising period (jiffies) */
 611         unsigned int bfq_wr_max_time;
 612
 613         /* Maximum weight-raising duration for soft real-time processes */
 614         unsigned int bfq_wr_rt_max_time;
 615         /*
 616          * Minimum idle period after which weight-raising may be
 617          * reactivated for a queue (in jiffies).
 618          */
 619         unsigned int bfq_wr_min_idle_time;
 620         /*
 621          * Minimum period between request arrivals after which
 622          * weight-raising may be reactivated for an already busy async
 623          * queue (in jiffies).
 624          */
 625         unsigned long bfq_wr_min_inter_arr_async;
 626
 627         /* Max service-rate for a soft real-time queue, in sectors/sec */
 628         unsigned int bfq_wr_max_softrt_rate;
 629         /*
 630          * Cached value of the product ref_rate*ref_wr_duration, used
 631          * for computing the maximum duration of weight raising
 632          * automatically.
 633          */
 634         u64 rate_dur_prod;
 635
 636         /* fallback dummy bfqq for extreme OOM conditions */
 637         struct bfq_queue oom_bfqq;
 638
 639         spinlock_t lock;
 640
 641         /*
 642          * bic associated with the task issuing current bio for
 643          * merging. This and the next field are used as a support to
 644          * be able to perform the bic lookup, needed by bio-merge
 645          * functions, before the scheduler lock is taken, and thus
 646          * avoid taking the request-queue lock while the scheduler
 647          * lock is being held.
 648          */
 649         struct bfq_io_cq *bio_bic;
 650         /* bfqq associated with the task issuing current bio for merging */
 651         struct bfq_queue *bio_bfqq;
 652
 653         /*
 654          * Depth limits used in bfq_limit_depth (see comments on the
 655          * function)
 656          */
 657         unsigned int word_depths[2][2];
 658 };
 659
 660 enum bfqq_state_flags {
 661         BFQQF_just_created = 0, /* queue just allocated */
 662         BFQQF_busy,             /* has requests or is in service */
 663         BFQQF_wait_request,     /* waiting for a request */
 664         BFQQF_non_blocking_wait_rq, /*
 665                                      * waiting for a request
 666                                      * without idling the device
 667                                      */
 668         BFQQF_fifo_expire,      /* FIFO checked in this slice */
 669         BFQQF_has_short_ttime,  /* queue has a short think time */
 670         BFQQF_sync,             /* synchronous queue */
 671         BFQQF_IO_bound,         /*
 672                                  * bfqq has timed-out at least once
 673                                  * having consumed at most 2/10 of
 674                                  * its budget
 675                                  */
 676         BFQQF_in_large_burst,   /*
 677                                  * bfqq activated in a large burst,
 678                                  * see comments to bfq_handle_burst.
 679                                  */
 680         BFQQF_softrt_update,    /*
 681                                  * may need softrt-next-start
 682                                  * update
 683                                  */
 684         BFQQF_coop,             /* bfqq is shared */
 685         BFQQF_split_coop        /* shared bfqq will be split */
 686 };
 687
 688 #define BFQ_BFQQ_FNS(name)                                              \
 689 void bfq_mark_bfqq_##name(struct bfq_queue *bfqq);                      \
 690 void bfq_clear_bfqq_##name(struct bfq_queue *bfqq);                     \
 691 int bfq_bfqq_##name(const struct bfq_queue *bfqq);
 692
 693 BFQ_BFQQ_FNS(just_created);
 694 BFQ_BFQQ_FNS(busy);
 695 BFQ_BFQQ_FNS(wait_request);
 696 BFQ_BFQQ_FNS(non_blocking_wait_rq);
 697 BFQ_BFQQ_FNS(fifo_expire);
 698 BFQ_BFQQ_FNS(has_short_ttime);
 699 BFQ_BFQQ_FNS(sync);
 700 BFQ_BFQQ_FNS(IO_bound);
 701 BFQ_BFQQ_FNS(in_large_burst);
 702 BFQ_BFQQ_FNS(coop);
 703 BFQ_BFQQ_FNS(split_coop);
 704 BFQ_BFQQ_FNS(softrt_update);
 705 #undef BFQ_BFQQ_FNS
 706
 707 /* Expiration reasons. */
 708 enum bfqq_expiration {
 709         BFQQE_TOO_IDLE = 0,             /*
 710                                          * queue has been idling for
 711                                          * too long
 712                                          */
 713         BFQQE_BUDGET_TIMEOUT,   /* budget took too long to be used */
 714         BFQQE_BUDGET_EXHAUSTED, /* budget consumed */
 715         BFQQE_NO_MORE_REQUESTS, /* the queue has no more requests */
 716         BFQQE_PREEMPTED         /* preemption in progress */
 717 };
 718
 719 struct bfqg_stats {
 720 #if defined(CONFIG_BFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
 721         /* number of ios merged */
 722         struct blkg_rwstat              merged;
 723         /* total time spent on device in ns, may not be accurate w/ queueing */
 724         struct blkg_rwstat              service_time;
 725         /* total time spent waiting in scheduler queue in ns */
 726         struct blkg_rwstat              wait_time;
 727         /* number of IOs queued up */
 728         struct blkg_rwstat              queued;
 729         /* total disk time and nr sectors dispatched by this group */
 730         struct blkg_stat                time;
 731         /* sum of number of ios queued across all samples */
 732         struct blkg_stat                avg_queue_size_sum;
 733         /* count of samples taken for average */
 734         struct blkg_stat                avg_queue_size_samples;
 735         /* how many times this group has been removed from service tree */
 736         struct blkg_stat                dequeue;
 737         /* total time spent waiting for it to be assigned a timeslice. */
 738         struct blkg_stat                group_wait_time;
 739         /* time spent idling for this blkcg_gq */
 740         struct blkg_stat                idle_time;
 741         /* total time with empty current active q with other requests queued */
 742         struct blkg_stat                empty_time;
 743         /* fields after this shouldn't be cleared on stat reset */
 744         u64                             start_group_wait_time;
 745         u64                             start_idle_time;
 746         u64                             start_empty_time;
 747         uint16_t                        flags;
 748 #endif  /* CONFIG_BFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
 749 };
 750
 751 #ifdef CONFIG_BFQ_GROUP_IOSCHED
 752
 753 /*
 754  * struct bfq_group_data - per-blkcg storage for the blkio subsystem.
 755  *
 756  * @ps: @blkcg_policy_storage that this structure inherits
 757  * @weight: weight of the bfq_group
 758  */
 759 struct bfq_group_data {
 760         /* must be the first member */
 761         struct blkcg_policy_data pd;
 762
 763         unsigned int weight;
 764 };
 765
 766 /**
 767  * struct bfq_group - per (device, cgroup) data structure.
 768  * @entity: schedulable entity to insert into the parent group sched_data.
 769  * @sched_data: own sched_data, to contain child entities (they may be
 770  *              both bfq_queues and bfq_groups).
 771  * @bfqd: the bfq_data for the device this group acts upon.
 772  * @async_bfqq: array of async queues for all the tasks belonging to
 773  *              the group, one queue per ioprio value per ioprio_class,
 774  *              except for the idle class that has only one queue.
 775  * @async_idle_bfqq: async queue for the idle class (ioprio is ignored).
 776  * @my_entity: pointer to @entity, %NULL for the toplevel group; used
 777  *             to avoid too many special cases during group creation/
 778  *             migration.
 779  * @stats: stats for this bfqg.
 780  * @active_entities: number of active entities belonging to the group;
 781  *                   unused for the root group. Used to know whether there
 782  *                   are groups with more than one active @bfq_entity
 783  *                   (see the comments to the function
 784  *                   bfq_bfqq_may_idle()).
 785  * @rq_pos_tree: rbtree sorted by next_request position, used when
 786  *               determining if two or more queues have interleaving
 787  *               requests (see bfq_find_close_cooperator()).
 788  *
 789  * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup
 790  * there is a set of bfq_groups, each one collecting the lower-level
 791  * entities belonging to the group that are acting on the same device.
 792  *
 793  * Locking works as follows:
 794  *    o @bfqd is protected by the queue lock, RCU is used to access it
 795  *      from the readers.
 796  *    o All the other fields are protected by the @bfqd queue lock.
 797  */
 798 struct bfq_group {
 799         /* must be the first member */
 800         struct blkg_policy_data pd;
 801
 802         /* cached path for this blkg (see comments in bfq_bic_update_cgroup) */
 803         char blkg_path[128];
 804
 805         /* reference counter (see comments in bfq_bic_update_cgroup) */
 806         int ref;
 807
 808         struct bfq_entity entity;
 809         struct bfq_sched_data sched_data;
 810
 811         void *bfqd;
 812
 813         struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
 814         struct bfq_queue *async_idle_bfqq;
 815
 816         struct bfq_entity *my_entity;
 817
 818         int active_entities;
 819
 820         struct rb_root rq_pos_tree;
 821
 822         struct bfqg_stats stats;
 823 };
 824
 825 #else
 826 struct bfq_group {
 827         struct bfq_sched_data sched_data;
 828
 829         struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
 830         struct bfq_queue *async_idle_bfqq;
 831
 832         struct rb_root rq_pos_tree;
 833 };
 834 #endif
 835
 836 struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
 837
 838 /* --------------- main algorithm interface ----------------- */
 839
 840 #define BFQ_SERVICE_TREE_INIT   ((struct bfq_service_tree)              \
 841                                 { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
 842
 843 extern const int bfq_timeout;
 844
 845 struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync);
 846 void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, bool is_sync);
 847 struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic);
 848 void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq);
 849 void bfq_weights_tree_add(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 850                           struct rb_root *root);
 851 void __bfq_weights_tree_remove(struct bfq_data *bfqd,
 852                                struct bfq_queue *bfqq,
 853                                struct rb_root *root);
 854 void bfq_weights_tree_remove(struct bfq_data *bfqd,
 855                              struct bfq_queue *bfqq);
 856 void bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 857                      bool compensate, enum bfqq_expiration reason);
 858 void bfq_put_queue(struct bfq_queue *bfqq);
 859 void bfq_end_wr_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
 860 void bfq_schedule_dispatch(struct bfq_data *bfqd);
 861 void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
 862
 863 /* ------------ end of main algorithm interface -------------- */
 864
 865 /* ---------------- cgroups-support interface ---------------- */
 866
 867 void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
 868                               unsigned int op);
 869 void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op);
 870 void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op);
 871 void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns,
 872                                   u64 io_start_time_ns, unsigned int op);
 873 void bfqg_stats_update_dequeue(struct bfq_group *bfqg);
 874 void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg);
 875 void bfqg_stats_update_idle_time(struct bfq_group *bfqg);
 876 void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg);
 877 void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg);
 878 void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 879                    struct bfq_group *bfqg);
 880
 881 void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg);
 882 void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio);
 883 void bfq_end_wr_async(struct bfq_data *bfqd);
 884 struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
 885                                      struct blkcg *blkcg);
 886 struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
 887 struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
 888 struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node);
 889 void bfqg_and_blkg_put(struct bfq_group *bfqg);
 890
 891 #ifdef CONFIG_BFQ_GROUP_IOSCHED
 892 extern struct cftype bfq_blkcg_legacy_files[];
 893 extern struct cftype bfq_blkg_files[];
 894 extern struct blkcg_policy blkcg_policy_bfq;
 895 #endif
 896
 897 /* ------------- end of cgroups-support interface ------------- */
 898
 899 /* - interface of the internal hierarchical B-WF2Q+ scheduler - */
 900
 901 #ifdef CONFIG_BFQ_GROUP_IOSCHED
 902 /* both next loops stop at one of the child entities of the root group */
 903 #define for_each_entity(entity) \
 904         for (; entity ; entity = entity->parent)
 905
 906 /*
 907  * For each iteration, compute parent in advance, so as to be safe if
 908  * entity is deallocated during the iteration. Such a deallocation may
 909  * happen as a consequence of a bfq_put_queue that frees the bfq_queue
 910  * containing entity.
 911  */
 912 #define for_each_entity_safe(entity, parent) \
 913         for (; entity && ({ parent = entity->parent; 1; }); entity = parent)
 914
 915 #else /* CONFIG_BFQ_GROUP_IOSCHED */
 916 /*
 917  * Next two macros are fake loops when cgroups support is not
 918  * enabled. I fact, in such a case, there is only one level to go up
 919  * (to reach the root group).
 920  */
 921 #define for_each_entity(entity) \
 922         for (; entity ; entity = NULL)
 923
 924 #define for_each_entity_safe(entity, parent) \
 925         for (parent = NULL; entity ; entity = parent)
 926 #endif /* CONFIG_BFQ_GROUP_IOSCHED */
 927
 928 struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq);
 929 struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
 930 struct bfq_service_tree *bfq_entity_service_tree(struct bfq_entity *entity);
 931 struct bfq_entity *bfq_entity_of(struct rb_node *node);
 932 unsigned short bfq_ioprio_to_weight(int ioprio);
 933 void bfq_put_idle_entity(struct bfq_service_tree *st,
 934                          struct bfq_entity *entity);
 935 struct bfq_service_tree *
 936 __bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
 937                                 struct bfq_entity *entity,
 938                                 bool update_class_too);
 939 void bfq_bfqq_served(struct bfq_queue *bfqq, int served);
 940 void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 941                           unsigned long time_ms);
 942 bool __bfq_deactivate_entity(struct bfq_entity *entity,
 943                              bool ins_into_idle_tree);
 944 bool next_queue_may_preempt(struct bfq_data *bfqd);
 945 struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd);
 946 void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd);
 947 void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 948                          bool ins_into_idle_tree, bool expiration);
 949 void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
 950 void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 951                       bool expiration);
 952 void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 953                        bool expiration);
 954 void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq);
 955
 956 /* --------------- end of interface of B-WF2Q+ ---------------- */
 957
 958 /* Logging facilities. */
 959 #ifdef CONFIG_BFQ_GROUP_IOSCHED
 960 struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
 961
 962 #define bfq_log_bfqq(bfqd, bfqq, fmt, args...)  do {                    \
 963         blk_add_cgroup_trace_msg((bfqd)->queue,                         \
 964                         bfqg_to_blkg(bfqq_group(bfqq))->blkcg,          \
 965                         "bfq%d%c " fmt, (bfqq)->pid,                    \
 966                         bfq_bfqq_sync((bfqq)) ? 'S' : 'A', ##args);     \
 967 } while (0)
 968
 969 #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)  do {                    \
 970         blk_add_cgroup_trace_msg((bfqd)->queue,                         \
 971                 bfqg_to_blkg(bfqg)->blkcg, fmt, ##args);                \
 972 } while (0)
 973
 974 #else /* CONFIG_BFQ_GROUP_IOSCHED */
 975
 976 #define bfq_log_bfqq(bfqd, bfqq, fmt, args...)  \
 977         blk_add_trace_msg((bfqd)->queue, "bfq%d%c " fmt, (bfqq)->pid,   \
 978                         bfq_bfqq_sync((bfqq)) ? 'S' : 'A',              \
 979                                 ##args)
 980 #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)          do {} while (0)
 981
 982 #endif /* CONFIG_BFQ_GROUP_IOSCHED */
 983
 984 #define bfq_log(bfqd, fmt, args...) \
 985         blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
 986
 987 #endif /* _BFQ_H */