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 on a hierarchical setup.  @next_in_service
  75  * points to the active entity of the sched_data service trees that
  76  * will be scheduled next. It is used to reduce the number of steps
  77  * needed for each hierarchical-schedule update.
  78  *
  79  * The supported ioprio_classes are the same as in CFQ, in descending
  80  * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE.
  81  * Requests from higher priority queues are served before all the
  82  * requests from lower priority queues; among requests of the same
  83  * queue requests are served according to B-WF2Q+.
  84  * All the fields are protected by the queue lock of the containing bfqd.
  85  */
  86 struct bfq_sched_data {
  87         /* entity in service */
  88         struct bfq_entity *in_service_entity;
  89         /* head-of-line entity (see comments above) */
  90         struct bfq_entity *next_in_service;
  91         /* array of service trees, one per ioprio_class */
  92         struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES];
  93         /* last time CLASS_IDLE was served */
  94         unsigned long bfq_class_idle_last_service;
  95
  96 };
  97
  98 /**
  99  * struct bfq_weight_counter - counter of the number of all active entities
 100  *                             with a given weight.
 101  */
 102 struct bfq_weight_counter {
 103         unsigned int weight; /* weight of the entities this counter refers to */
 104         unsigned int num_active; /* nr of active entities with this weight */
 105         /*
 106          * Weights tree member (see bfq_data's @queue_weights_tree and
 107          * @group_weights_tree)
 108          */
 109         struct rb_node weights_node;
 110 };
 111
 112 /**
 113  * struct bfq_entity - schedulable entity.
 114  *
 115  * A bfq_entity is used to represent either a bfq_queue (leaf node in the
 116  * cgroup hierarchy) or a bfq_group into the upper level scheduler.  Each
 117  * entity belongs to the sched_data of the parent group in the cgroup
 118  * hierarchy.  Non-leaf entities have also their own sched_data, stored
 119  * in @my_sched_data.
 120  *
 121  * Each entity stores independently its priority values; this would
 122  * allow different weights on different devices, but this
 123  * functionality is not exported to userspace by now.  Priorities and
 124  * weights are updated lazily, first storing the new values into the
 125  * new_* fields, then setting the @prio_changed flag.  As soon as
 126  * there is a transition in the entity state that allows the priority
 127  * update to take place the effective and the requested priority
 128  * values are synchronized.
 129  *
 130  * Unless cgroups are used, the weight value is calculated from the
 131  * ioprio to export the same interface as CFQ.  When dealing with
 132  * ``well-behaved'' queues (i.e., queues that do not spend too much
 133  * time to consume their budget and have true sequential behavior, and
 134  * when there are no external factors breaking anticipation) the
 135  * relative weights at each level of the cgroups hierarchy should be
 136  * guaranteed.  All the fields are protected by the queue lock of the
 137  * containing bfqd.
 138  */
 139 struct bfq_entity {
 140         /* service_tree member */
 141         struct rb_node rb_node;
 142         /* pointer to the weight counter associated with this entity */
 143         struct bfq_weight_counter *weight_counter;
 144
 145         /*
 146          * Flag, true if the entity is on a tree (either the active or
 147          * the idle one of its service_tree) or is in service.
 148          */
 149         bool on_st;
 150
 151         /* B-WF2Q+ start and finish timestamps [sectors/weight] */
 152         u64 start, finish;
 153
 154         /* tree the entity is enqueued into; %NULL if not on a tree */
 155         struct rb_root *tree;
 156
 157         /*
 158          * minimum start time of the (active) subtree rooted at this
 159          * entity; used for O(log N) lookups into active trees
 160          */
 161         u64 min_start;
 162
 163         /* amount of service received during the last service slot */
 164         int service;
 165
 166         /* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */
 167         int budget;
 168
 169         /* weight of the queue */
 170         int weight;
 171         /* next weight if a change is in progress */
 172         int new_weight;
 173
 174         /* original weight, used to implement weight boosting */
 175         int orig_weight;
 176
 177         /* parent entity, for hierarchical scheduling */
 178         struct bfq_entity *parent;
 179
 180         /*
 181          * For non-leaf nodes in the hierarchy, the associated
 182          * scheduler queue, %NULL on leaf nodes.
 183          */
 184         struct bfq_sched_data *my_sched_data;
 185         /* the scheduler queue this entity belongs to */
 186         struct bfq_sched_data *sched_data;
 187
 188         /* flag, set to request a weight, ioprio or ioprio_class change  */
 189         int prio_changed;
 190 };
 191
 192 struct bfq_group;
 193
 194 /**
 195  * struct bfq_ttime - per process thinktime stats.
 196  */
 197 struct bfq_ttime {
 198         /* completion time of the last request */
 199         u64 last_end_request;
 200
 201         /* total process thinktime */
 202         u64 ttime_total;
 203         /* number of thinktime samples */
 204         unsigned long ttime_samples;
 205         /* average process thinktime */
 206         u64 ttime_mean;
 207 };
 208
 209 /**
 210  * struct bfq_queue - leaf schedulable entity.
 211  *
 212  * A bfq_queue is a leaf request queue; it can be associated with an
 213  * io_context or more, if it  is  async or shared  between  cooperating
 214  * processes. @cgroup holds a reference to the cgroup, to be sure that it
 215  * does not disappear while a bfqq still references it (mostly to avoid
 216  * races between request issuing and task migration followed by cgroup
 217  * destruction).
 218  * All the fields are protected by the queue lock of the containing bfqd.
 219  */
 220 struct bfq_queue {
 221         /* reference counter */
 222         int ref;
 223         /* parent bfq_data */
 224         struct bfq_data *bfqd;
 225
 226         /* current ioprio and ioprio class */
 227         unsigned short ioprio, ioprio_class;
 228         /* next ioprio and ioprio class if a change is in progress */
 229         unsigned short new_ioprio, new_ioprio_class;
 230
 231         /*
 232          * Shared bfq_queue if queue is cooperating with one or more
 233          * other queues.
 234          */
 235         struct bfq_queue *new_bfqq;
 236         /* request-position tree member (see bfq_group's @rq_pos_tree) */
 237         struct rb_node pos_node;
 238         /* request-position tree root (see bfq_group's @rq_pos_tree) */
 239         struct rb_root *pos_root;
 240
 241         /* sorted list of pending requests */
 242         struct rb_root sort_list;
 243         /* if fifo isn't expired, next request to serve */
 244         struct request *next_rq;
 245         /* number of sync and async requests queued */
 246         int queued[2];
 247         /* number of requests currently allocated */
 248         int allocated;
 249         /* number of pending metadata requests */
 250         int meta_pending;
 251         /* fifo list of requests in sort_list */
 252         struct list_head fifo;
 253
 254         /* entity representing this queue in the scheduler */
 255         struct bfq_entity entity;
 256
 257         /* maximum budget allowed from the feedback mechanism */
 258         int max_budget;
 259         /* budget expiration (in jiffies) */
 260         unsigned long budget_timeout;
 261
 262         /* number of requests on the dispatch list or inside driver */
 263         int dispatched;
 264
 265         /* status flags */
 266         unsigned long flags;
 267
 268         /* node for active/idle bfqq list inside parent bfqd */
 269         struct list_head bfqq_list;
 270
 271         /* associated @bfq_ttime struct */
 272         struct bfq_ttime ttime;
 273
 274         /* bit vector: a 1 for each seeky requests in history */
 275         u32 seek_history;
 276
 277         /* node for the device's burst list */
 278         struct hlist_node burst_list_node;
 279
 280         /* position of the last request enqueued */
 281         sector_t last_request_pos;
 282
 283         /* Number of consecutive pairs of request completion and
 284          * arrival, such that the queue becomes idle after the
 285          * completion, but the next request arrives within an idle
 286          * time slice; used only if the queue's IO_bound flag has been
 287          * cleared.
 288          */
 289         unsigned int requests_within_timer;
 290
 291         /* pid of the process owning the queue, used for logging purposes */
 292         pid_t pid;
 293
 294         /*
 295          * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL
 296          * if the queue is shared.
 297          */
 298         struct bfq_io_cq *bic;
 299
 300         /* current maximum weight-raising time for this queue */
 301         unsigned long wr_cur_max_time;
 302         /*
 303          * Minimum time instant such that, only if a new request is
 304          * enqueued after this time instant in an idle @bfq_queue with
 305          * no outstanding requests, then the task associated with the
 306          * queue it is deemed as soft real-time (see the comments on
 307          * the function bfq_bfqq_softrt_next_start())
 308          */
 309         unsigned long soft_rt_next_start;
 310         /*
 311          * Start time of the current weight-raising period if
 312          * the @bfq-queue is being weight-raised, otherwise
 313          * finish time of the last weight-raising period.
 314          */
 315         unsigned long last_wr_start_finish;
 316         /* factor by which the weight of this queue is multiplied */
 317         unsigned int wr_coeff;
 318         /*
 319          * Time of the last transition of the @bfq_queue from idle to
 320          * backlogged.
 321          */
 322         unsigned long last_idle_bklogged;
 323         /*
 324          * Cumulative service received from the @bfq_queue since the
 325          * last transition from idle to backlogged.
 326          */
 327         unsigned long service_from_backlogged;
 328
 329         /*
 330          * Value of wr start time when switching to soft rt
 331          */
 332         unsigned long wr_start_at_switch_to_srt;
 333
 334         unsigned long split_time; /* time of last split */
 335 };
 336
 337 /**
 338  * struct bfq_io_cq - per (request_queue, io_context) structure.
 339  */
 340 struct bfq_io_cq {
 341         /* associated io_cq structure */
 342         struct io_cq icq; /* must be the first member */
 343         /* array of two process queues, the sync and the async */
 344         struct bfq_queue *bfqq[2];
 345         /* per (request_queue, blkcg) ioprio */
 346         int ioprio;
 347 #ifdef CONFIG_BFQ_GROUP_IOSCHED
 348         uint64_t blkcg_serial_nr; /* the current blkcg serial */
 349 #endif
 350         /*
 351          * Snapshot of the idle window before merging; taken to
 352          * remember this value while the queue is merged, so as to be
 353          * able to restore it in case of split.
 354          */
 355         bool saved_idle_window;
 356         /*
 357          * Same purpose as the previous two fields for the I/O bound
 358          * classification of a queue.
 359          */
 360         bool saved_IO_bound;
 361
 362         /*
 363          * Same purpose as the previous fields for the value of the
 364          * field keeping the queue's belonging to a large burst
 365          */
 366         bool saved_in_large_burst;
 367         /*
 368          * True if the queue belonged to a burst list before its merge
 369          * with another cooperating queue.
 370          */
 371         bool was_in_burst_list;
 372
 373         /*
 374          * Similar to previous fields: save wr information.
 375          */
 376         unsigned long saved_wr_coeff;
 377         unsigned long saved_last_wr_start_finish;
 378         unsigned long saved_wr_start_at_switch_to_srt;
 379         unsigned int saved_wr_cur_max_time;
 380         struct bfq_ttime saved_ttime;
 381 };
 382
 383 enum bfq_device_speed {
 384         BFQ_BFQD_FAST,
 385         BFQ_BFQD_SLOW,
 386 };
 387
 388 /**
 389  * struct bfq_data - per-device data structure.
 390  *
 391  * All the fields are protected by @lock.
 392  */
 393 struct bfq_data {
 394         /* device request queue */
 395         struct request_queue *queue;
 396         /* dispatch queue */
 397         struct list_head dispatch;
 398
 399         /* root bfq_group for the device */
 400         struct bfq_group *root_group;
 401
 402         /*
 403          * rbtree of weight counters of @bfq_queues, sorted by
 404          * weight. Used to keep track of whether all @bfq_queues have
 405          * the same weight. The tree contains one counter for each
 406          * distinct weight associated to some active and not
 407          * weight-raised @bfq_queue (see the comments to the functions
 408          * bfq_weights_tree_[add|remove] for further details).
 409          */
 410         struct rb_root queue_weights_tree;
 411         /*
 412          * rbtree of non-queue @bfq_entity weight counters, sorted by
 413          * weight. Used to keep track of whether all @bfq_groups have
 414          * the same weight. The tree contains one counter for each
 415          * distinct weight associated to some active @bfq_group (see
 416          * the comments to the functions bfq_weights_tree_[add|remove]
 417          * for further details).
 418          */
 419         struct rb_root group_weights_tree;
 420
 421         /*
 422          * Number of bfq_queues containing requests (including the
 423          * queue in service, even if it is idling).
 424          */
 425         int busy_queues;
 426         /* number of weight-raised busy @bfq_queues */
 427         int wr_busy_queues;
 428         /* number of queued requests */
 429         int queued;
 430         /* number of requests dispatched and waiting for completion */
 431         int rq_in_driver;
 432
 433         /*
 434          * Maximum number of requests in driver in the last
 435          * @hw_tag_samples completed requests.
 436          */
 437         int max_rq_in_driver;
 438         /* number of samples used to calculate hw_tag */
 439         int hw_tag_samples;
 440         /* flag set to one if the driver is showing a queueing behavior */
 441         int hw_tag;
 442
 443         /* number of budgets assigned */
 444         int budgets_assigned;
 445
 446         /*
 447          * Timer set when idling (waiting) for the next request from
 448          * the queue in service.
 449          */
 450         struct hrtimer idle_slice_timer;
 451
 452         /* bfq_queue in service */
 453         struct bfq_queue *in_service_queue;
 454
 455         /* on-disk position of the last served request */
 456         sector_t last_position;
 457
 458         /* time of last request completion (ns) */
 459         u64 last_completion;
 460
 461         /* time of first rq dispatch in current observation interval (ns) */
 462         u64 first_dispatch;
 463         /* time of last rq dispatch in current observation interval (ns) */
 464         u64 last_dispatch;
 465
 466         /* beginning of the last budget */
 467         ktime_t last_budget_start;
 468         /* beginning of the last idle slice */
 469         ktime_t last_idling_start;
 470
 471         /* number of samples in current observation interval */
 472         int peak_rate_samples;
 473         /* num of samples of seq dispatches in current observation interval */
 474         u32 sequential_samples;
 475         /* total num of sectors transferred in current observation interval */
 476         u64 tot_sectors_dispatched;
 477         /* max rq size seen during current observation interval (sectors) */
 478         u32 last_rq_max_size;
 479         /* time elapsed from first dispatch in current observ. interval (us) */
 480         u64 delta_from_first;
 481         /*
 482          * Current estimate of the device peak rate, measured in
 483          * [BFQ_RATE_SHIFT * sectors/usec]. The left-shift by
 484          * BFQ_RATE_SHIFT is performed to increase precision in
 485          * fixed-point calculations.
 486          */
 487         u32 peak_rate;
 488
 489         /* maximum budget allotted to a bfq_queue before rescheduling */
 490         int bfq_max_budget;
 491
 492         /* list of all the bfq_queues active on the device */
 493         struct list_head active_list;
 494         /* list of all the bfq_queues idle on the device */
 495         struct list_head idle_list;
 496
 497         /*
 498          * Timeout for async/sync requests; when it fires, requests
 499          * are served in fifo order.
 500          */
 501         u64 bfq_fifo_expire[2];
 502         /* weight of backward seeks wrt forward ones */
 503         unsigned int bfq_back_penalty;
 504         /* maximum allowed backward seek */
 505         unsigned int bfq_back_max;
 506         /* maximum idling time */
 507         u32 bfq_slice_idle;
 508
 509         /* user-configured max budget value (0 for auto-tuning) */
 510         int bfq_user_max_budget;
 511         /*
 512          * Timeout for bfq_queues to consume their budget; used to
 513          * prevent seeky queues from imposing long latencies to
 514          * sequential or quasi-sequential ones (this also implies that
 515          * seeky queues cannot receive guarantees in the service
 516          * domain; after a timeout they are charged for the time they
 517          * have been in service, to preserve fairness among them, but
 518          * without service-domain guarantees).
 519          */
 520         unsigned int bfq_timeout;
 521
 522         /*
 523          * Number of consecutive requests that must be issued within
 524          * the idle time slice to set again idling to a queue which
 525          * was marked as non-I/O-bound (see the definition of the
 526          * IO_bound flag for further details).
 527          */
 528         unsigned int bfq_requests_within_timer;
 529
 530         /*
 531          * Force device idling whenever needed to provide accurate
 532          * service guarantees, without caring about throughput
 533          * issues. CAVEAT: this may even increase latencies, in case
 534          * of useless idling for processes that did stop doing I/O.
 535          */
 536         bool strict_guarantees;
 537
 538         /*
 539          * Last time at which a queue entered the current burst of
 540          * queues being activated shortly after each other; for more
 541          * details about this and the following parameters related to
 542          * a burst of activations, see the comments on the function
 543          * bfq_handle_burst.
 544          */
 545         unsigned long last_ins_in_burst;
 546         /*
 547          * Reference time interval used to decide whether a queue has
 548          * been activated shortly after @last_ins_in_burst.
 549          */
 550         unsigned long bfq_burst_interval;
 551         /* number of queues in the current burst of queue activations */
 552         int burst_size;
 553
 554         /* common parent entity for the queues in the burst */
 555         struct bfq_entity *burst_parent_entity;
 556         /* Maximum burst size above which the current queue-activation
 557          * burst is deemed as 'large'.
 558          */
 559         unsigned long bfq_large_burst_thresh;
 560         /* true if a large queue-activation burst is in progress */
 561         bool large_burst;
 562         /*
 563          * Head of the burst list (as for the above fields, more
 564          * details in the comments on the function bfq_handle_burst).
 565          */
 566         struct hlist_head burst_list;
 567
 568         /* if set to true, low-latency heuristics are enabled */
 569         bool low_latency;
 570         /*
 571          * Maximum factor by which the weight of a weight-raised queue
 572          * is multiplied.
 573          */
 574         unsigned int bfq_wr_coeff;
 575         /* maximum duration of a weight-raising period (jiffies) */
 576         unsigned int bfq_wr_max_time;
 577
 578         /* Maximum weight-raising duration for soft real-time processes */
 579         unsigned int bfq_wr_rt_max_time;
 580         /*
 581          * Minimum idle period after which weight-raising may be
 582          * reactivated for a queue (in jiffies).
 583          */
 584         unsigned int bfq_wr_min_idle_time;
 585         /*
 586          * Minimum period between request arrivals after which
 587          * weight-raising may be reactivated for an already busy async
 588          * queue (in jiffies).
 589          */
 590         unsigned long bfq_wr_min_inter_arr_async;
 591
 592         /* Max service-rate for a soft real-time queue, in sectors/sec */
 593         unsigned int bfq_wr_max_softrt_rate;
 594         /*
 595          * Cached value of the product R*T, used for computing the
 596          * maximum duration of weight raising automatically.
 597          */
 598         u64 RT_prod;
 599         /* device-speed class for the low-latency heuristic */
 600         enum bfq_device_speed device_speed;
 601
 602         /* fallback dummy bfqq for extreme OOM conditions */
 603         struct bfq_queue oom_bfqq;
 604
 605         spinlock_t lock;
 606
 607         /*
 608          * bic associated with the task issuing current bio for
 609          * merging. This and the next field are used as a support to
 610          * be able to perform the bic lookup, needed by bio-merge
 611          * functions, before the scheduler lock is taken, and thus
 612          * avoid taking the request-queue lock while the scheduler
 613          * lock is being held.
 614          */
 615         struct bfq_io_cq *bio_bic;
 616         /* bfqq associated with the task issuing current bio for merging */
 617         struct bfq_queue *bio_bfqq;
 618 };
 619
 620 enum bfqq_state_flags {
 621         BFQQF_just_created = 0, /* queue just allocated */
 622         BFQQF_busy,             /* has requests or is in service */
 623         BFQQF_wait_request,     /* waiting for a request */
 624         BFQQF_non_blocking_wait_rq, /*
 625                                      * waiting for a request
 626                                      * without idling the device
 627                                      */
 628         BFQQF_fifo_expire,      /* FIFO checked in this slice */
 629         BFQQF_idle_window,      /* slice idling enabled */
 630         BFQQF_sync,             /* synchronous queue */
 631         BFQQF_IO_bound,         /*
 632                                  * bfqq has timed-out at least once
 633                                  * having consumed at most 2/10 of
 634                                  * its budget
 635                                  */
 636         BFQQF_in_large_burst,   /*
 637                                  * bfqq activated in a large burst,
 638                                  * see comments to bfq_handle_burst.
 639                                  */
 640         BFQQF_softrt_update,    /*
 641                                  * may need softrt-next-start
 642                                  * update
 643                                  */
 644         BFQQF_coop,             /* bfqq is shared */
 645         BFQQF_split_coop        /* shared bfqq will be split */
 646 };
 647
 648 #define BFQ_BFQQ_FNS(name)                                              \
 649 void bfq_mark_bfqq_##name(struct bfq_queue *bfqq);                      \
 650 void bfq_clear_bfqq_##name(struct bfq_queue *bfqq);                     \
 651 int bfq_bfqq_##name(const struct bfq_queue *bfqq);
 652
 653 BFQ_BFQQ_FNS(just_created);
 654 BFQ_BFQQ_FNS(busy);
 655 BFQ_BFQQ_FNS(wait_request);
 656 BFQ_BFQQ_FNS(non_blocking_wait_rq);
 657 BFQ_BFQQ_FNS(fifo_expire);
 658 BFQ_BFQQ_FNS(idle_window);
 659 BFQ_BFQQ_FNS(sync);
 660 BFQ_BFQQ_FNS(IO_bound);
 661 BFQ_BFQQ_FNS(in_large_burst);
 662 BFQ_BFQQ_FNS(coop);
 663 BFQ_BFQQ_FNS(split_coop);
 664 BFQ_BFQQ_FNS(softrt_update);
 665 #undef BFQ_BFQQ_FNS
 666
 667 /* Expiration reasons. */
 668 enum bfqq_expiration {
 669         BFQQE_TOO_IDLE = 0,             /*
 670                                          * queue has been idling for
 671                                          * too long
 672                                          */
 673         BFQQE_BUDGET_TIMEOUT,   /* budget took too long to be used */
 674         BFQQE_BUDGET_EXHAUSTED, /* budget consumed */
 675         BFQQE_NO_MORE_REQUESTS, /* the queue has no more requests */
 676         BFQQE_PREEMPTED         /* preemption in progress */
 677 };
 678
 679 struct bfqg_stats {
 680 #ifdef CONFIG_BFQ_GROUP_IOSCHED
 681         /* number of ios merged */
 682         struct blkg_rwstat              merged;
 683         /* total time spent on device in ns, may not be accurate w/ queueing */
 684         struct blkg_rwstat              service_time;
 685         /* total time spent waiting in scheduler queue in ns */
 686         struct blkg_rwstat              wait_time;
 687         /* number of IOs queued up */
 688         struct blkg_rwstat              queued;
 689         /* total disk time and nr sectors dispatched by this group */
 690         struct blkg_stat                time;
 691         /* sum of number of ios queued across all samples */
 692         struct blkg_stat                avg_queue_size_sum;
 693         /* count of samples taken for average */
 694         struct blkg_stat                avg_queue_size_samples;
 695         /* how many times this group has been removed from service tree */
 696         struct blkg_stat                dequeue;
 697         /* total time spent waiting for it to be assigned a timeslice. */
 698         struct blkg_stat                group_wait_time;
 699         /* time spent idling for this blkcg_gq */
 700         struct blkg_stat                idle_time;
 701         /* total time with empty current active q with other requests queued */
 702         struct blkg_stat                empty_time;
 703         /* fields after this shouldn't be cleared on stat reset */
 704         uint64_t                        start_group_wait_time;
 705         uint64_t                        start_idle_time;
 706         uint64_t                        start_empty_time;
 707         uint16_t                        flags;
 708 #endif  /* CONFIG_BFQ_GROUP_IOSCHED */
 709 };
 710
 711 #ifdef CONFIG_BFQ_GROUP_IOSCHED
 712
 713 /*
 714  * struct bfq_group_data - per-blkcg storage for the blkio subsystem.
 715  *
 716  * @ps: @blkcg_policy_storage that this structure inherits
 717  * @weight: weight of the bfq_group
 718  */
 719 struct bfq_group_data {
 720         /* must be the first member */
 721         struct blkcg_policy_data pd;
 722
 723         unsigned int weight;
 724 };
 725
 726 /**
 727  * struct bfq_group - per (device, cgroup) data structure.
 728  * @entity: schedulable entity to insert into the parent group sched_data.
 729  * @sched_data: own sched_data, to contain child entities (they may be
 730  *              both bfq_queues and bfq_groups).
 731  * @bfqd: the bfq_data for the device this group acts upon.
 732  * @async_bfqq: array of async queues for all the tasks belonging to
 733  *              the group, one queue per ioprio value per ioprio_class,
 734  *              except for the idle class that has only one queue.
 735  * @async_idle_bfqq: async queue for the idle class (ioprio is ignored).
 736  * @my_entity: pointer to @entity, %NULL for the toplevel group; used
 737  *             to avoid too many special cases during group creation/
 738  *             migration.
 739  * @stats: stats for this bfqg.
 740  * @active_entities: number of active entities belonging to the group;
 741  *                   unused for the root group. Used to know whether there
 742  *                   are groups with more than one active @bfq_entity
 743  *                   (see the comments to the function
 744  *                   bfq_bfqq_may_idle()).
 745  * @rq_pos_tree: rbtree sorted by next_request position, used when
 746  *               determining if two or more queues have interleaving
 747  *               requests (see bfq_find_close_cooperator()).
 748  *
 749  * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup
 750  * there is a set of bfq_groups, each one collecting the lower-level
 751  * entities belonging to the group that are acting on the same device.
 752  *
 753  * Locking works as follows:
 754  *    o @bfqd is protected by the queue lock, RCU is used to access it
 755  *      from the readers.
 756  *    o All the other fields are protected by the @bfqd queue lock.
 757  */
 758 struct bfq_group {
 759         /* must be the first member */
 760         struct blkg_policy_data pd;
 761
 762         /* cached path for this blkg (see comments in bfq_bic_update_cgroup) */
 763         char blkg_path[128];
 764
 765         /* reference counter (see comments in bfq_bic_update_cgroup) */
 766         int ref;
 767
 768         struct bfq_entity entity;
 769         struct bfq_sched_data sched_data;
 770
 771         void *bfqd;
 772
 773         struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
 774         struct bfq_queue *async_idle_bfqq;
 775
 776         struct bfq_entity *my_entity;
 777
 778         int active_entities;
 779
 780         struct rb_root rq_pos_tree;
 781
 782         struct bfqg_stats stats;
 783 };
 784
 785 #else
 786 struct bfq_group {
 787         struct bfq_sched_data sched_data;
 788
 789         struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
 790         struct bfq_queue *async_idle_bfqq;
 791
 792         struct rb_root rq_pos_tree;
 793 };
 794 #endif
 795
 796 struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
 797
 798 /* --------------- main algorithm interface ----------------- */
 799
 800 #define BFQ_SERVICE_TREE_INIT   ((struct bfq_service_tree)              \
 801                                 { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
 802
 803 extern const int bfq_timeout;
 804
 805 struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync);
 806 void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, bool is_sync);
 807 struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic);
 808 void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
 809 void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq);
 810 void bfq_weights_tree_add(struct bfq_data *bfqd, struct bfq_entity *entity,
 811                           struct rb_root *root);
 812 void bfq_weights_tree_remove(struct bfq_data *bfqd, struct bfq_entity *entity,
 813                              struct rb_root *root);
 814 void bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 815                      bool compensate, enum bfqq_expiration reason);
 816 void bfq_put_queue(struct bfq_queue *bfqq);
 817 void bfq_end_wr_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
 818 void bfq_schedule_dispatch(struct bfq_data *bfqd);
 819 void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
 820
 821 /* ------------ end of main algorithm interface -------------- */
 822
 823 /* ---------------- cgroups-support interface ---------------- */
 824
 825 void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
 826                               unsigned int op);
 827 void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op);
 828 void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op);
 829 void bfqg_stats_update_completion(struct bfq_group *bfqg, uint64_t start_time,
 830                                   uint64_t io_start_time, unsigned int op);
 831 void bfqg_stats_update_dequeue(struct bfq_group *bfqg);
 832 void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg);
 833 void bfqg_stats_update_idle_time(struct bfq_group *bfqg);
 834 void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg);
 835 void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg);
 836 void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 837                    struct bfq_group *bfqg);
 838
 839 void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg);
 840 void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio);
 841 void bfq_end_wr_async(struct bfq_data *bfqd);
 842 struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
 843                                      struct blkcg *blkcg);
 844 struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
 845 struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
 846 struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node);
 847 void bfqg_and_blkg_put(struct bfq_group *bfqg);
 848
 849 #ifdef CONFIG_BFQ_GROUP_IOSCHED
 850 extern struct cftype bfq_blkcg_legacy_files[];
 851 extern struct cftype bfq_blkg_files[];
 852 extern struct blkcg_policy blkcg_policy_bfq;
 853 #endif
 854
 855 /* ------------- end of cgroups-support interface ------------- */
 856
 857 /* - interface of the internal hierarchical B-WF2Q+ scheduler - */
 858
 859 #ifdef CONFIG_BFQ_GROUP_IOSCHED
 860 /* both next loops stop at one of the child entities of the root group */
 861 #define for_each_entity(entity) \
 862         for (; entity ; entity = entity->parent)
 863
 864 /*
 865  * For each iteration, compute parent in advance, so as to be safe if
 866  * entity is deallocated during the iteration. Such a deallocation may
 867  * happen as a consequence of a bfq_put_queue that frees the bfq_queue
 868  * containing entity.
 869  */
 870 #define for_each_entity_safe(entity, parent) \
 871         for (; entity && ({ parent = entity->parent; 1; }); entity = parent)
 872
 873 #else /* CONFIG_BFQ_GROUP_IOSCHED */
 874 /*
 875  * Next two macros are fake loops when cgroups support is not
 876  * enabled. I fact, in such a case, there is only one level to go up
 877  * (to reach the root group).
 878  */
 879 #define for_each_entity(entity) \
 880         for (; entity ; entity = NULL)
 881
 882 #define for_each_entity_safe(entity, parent) \
 883         for (parent = NULL; entity ; entity = parent)
 884 #endif /* CONFIG_BFQ_GROUP_IOSCHED */
 885
 886 struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq);
 887 struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
 888 struct bfq_service_tree *bfq_entity_service_tree(struct bfq_entity *entity);
 889 struct bfq_entity *bfq_entity_of(struct rb_node *node);
 890 unsigned short bfq_ioprio_to_weight(int ioprio);
 891 void bfq_put_idle_entity(struct bfq_service_tree *st,
 892                          struct bfq_entity *entity);
 893 struct bfq_service_tree *
 894 __bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
 895                                 struct bfq_entity *entity,
 896                                 bool update_class_too);
 897 void bfq_bfqq_served(struct bfq_queue *bfqq, int served);
 898 void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 899                           unsigned long time_ms);
 900 bool __bfq_deactivate_entity(struct bfq_entity *entity,
 901                              bool ins_into_idle_tree);
 902 bool next_queue_may_preempt(struct bfq_data *bfqd);
 903 struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd);
 904 void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd);
 905 void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 906                          bool ins_into_idle_tree, bool expiration);
 907 void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
 908 void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
 909 void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 910                        bool expiration);
 911 void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq);
 912
 913 /* --------------- end of interface of B-WF2Q+ ---------------- */
 914
 915 /* Logging facilities. */
 916 #ifdef CONFIG_BFQ_GROUP_IOSCHED
 917 struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
 918
 919 #define bfq_log_bfqq(bfqd, bfqq, fmt, args...)  do {                    \
 920         blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s " fmt, (bfqq)->pid,\
 921                         bfq_bfqq_sync((bfqq)) ? 'S' : 'A',              \
 922                         bfqq_group(bfqq)->blkg_path, ##args);           \
 923 } while (0)
 924
 925 #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)  \
 926         blk_add_trace_msg((bfqd)->queue, "%s " fmt, (bfqg)->blkg_path, ##args)
 927
 928 #else /* CONFIG_BFQ_GROUP_IOSCHED */
 929
 930 #define bfq_log_bfqq(bfqd, bfqq, fmt, args...)  \
 931         blk_add_trace_msg((bfqd)->queue, "bfq%d%c " fmt, (bfqq)->pid,   \
 932                         bfq_bfqq_sync((bfqq)) ? 'S' : 'A',              \
 933                                 ##args)
 934 #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)          do {} while (0)
 935
 936 #endif /* CONFIG_BFQ_GROUP_IOSCHED */
 937
 938 #define bfq_log(bfqd, fmt, args...) \
 939         blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
 940
 941 #endif /* _BFQ_H */