cregit-Linux how code gets into the kernel

Release 4.12 block/bfq-iosched.h

Directory: block
 * Header file for the BFQ I/O scheduler: data structures and
 * prototypes of interface functions among BFQ components.
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License as
 *  published by the Free Software Foundation; either version 2 of the
 *  License, or (at your option) any later version.
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  General Public License for more details.
#ifndef _BFQ_H

#define _BFQ_H

#include <linux/blktrace_api.h>
#include <linux/hrtimer.h>
#include <linux/blk-cgroup.h>



#define BFQ_MIN_WEIGHT			1

#define BFQ_MAX_WEIGHT			1000






 * Soft real-time applications are extremely more latency sensitive
 * than interactive ones. Over-raise the weight of the former to
 * privilege them against the latter.


struct bfq_entity;

 * struct bfq_service_tree - per ioprio_class service tree.
 * Each service tree represents a B-WF2Q+ scheduler on its own.  Each
 * ioprio_class has its own independent scheduler, and so its own
 * bfq_service_tree.  All the fields are protected by the queue lock
 * of the containing bfqd.

struct bfq_service_tree {
	/* tree for active entities (i.e., those backlogged) */
struct rb_root active;
	/* tree for idle entities (i.e., not backlogged, with V <= F_i)*/
struct rb_root idle;

	/* idle entity with minimum F_i */
struct bfq_entity *first_idle;
	/* idle entity with maximum F_i */
struct bfq_entity *last_idle;

	/* scheduler virtual time */
u64 vtime;
	/* scheduler weight sum; active and idle entities contribute to it */
unsigned long wsum;

 * struct bfq_sched_data - multi-class scheduler.
 * bfq_sched_data is the basic scheduler queue.  It supports three
 * ioprio_classes, and can be used either as a toplevel queue or as an
 * intermediate queue on a hierarchical setup.  @next_in_service
 * points to the active entity of the sched_data service trees that
 * will be scheduled next. It is used to reduce the number of steps
 * needed for each hierarchical-schedule update.
 * The supported ioprio_classes are the same as in CFQ, in descending
 * Requests from higher priority queues are served before all the
 * requests from lower priority queues; among requests of the same
 * queue requests are served according to B-WF2Q+.
 * All the fields are protected by the queue lock of the containing bfqd.

struct bfq_sched_data {
	/* entity in service */
struct bfq_entity *in_service_entity;
	/* head-of-line entity (see comments above) */
struct bfq_entity *next_in_service;
	/* array of service trees, one per ioprio_class */
struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES];
	/* last time CLASS_IDLE was served */
unsigned long bfq_class_idle_last_service;


 * struct bfq_weight_counter - counter of the number of all active entities
 *                             with a given weight.

struct bfq_weight_counter {
unsigned int weight; /* weight of the entities this counter refers to */
unsigned int num_active; /* nr of active entities with this weight */
         * Weights tree member (see bfq_data's @queue_weights_tree and
         * @group_weights_tree)
struct rb_node weights_node;

 * struct bfq_entity - schedulable entity.
 * A bfq_entity is used to represent either a bfq_queue (leaf node in the
 * cgroup hierarchy) or a bfq_group into the upper level scheduler.  Each
 * entity belongs to the sched_data of the parent group in the cgroup
 * hierarchy.  Non-leaf entities have also their own sched_data, stored
 * in @my_sched_data.
 * Each entity stores independently its priority values; this would
 * allow different weights on different devices, but this
 * functionality is not exported to userspace by now.  Priorities and
 * weights are updated lazily, first storing the new values into the
 * new_* fields, then setting the @prio_changed flag.  As soon as
 * there is a transition in the entity state that allows the priority
 * update to take place the effective and the requested priority
 * values are synchronized.
 * Unless cgroups are used, the weight value is calculated from the
 * ioprio to export the same interface as CFQ.  When dealing with
 * ``well-behaved'' queues (i.e., queues that do not spend too much
 * time to consume their budget and have true sequential behavior, and
 * when there are no external factors breaking anticipation) the
 * relative weights at each level of the cgroups hierarchy should be
 * guaranteed.  All the fields are protected by the queue lock of the
 * containing bfqd.

struct bfq_entity {
	/* service_tree member */
struct rb_node rb_node;
	/* pointer to the weight counter associated with this entity */
struct bfq_weight_counter *weight_counter;

         * Flag, true if the entity is on a tree (either the active or
         * the idle one of its service_tree) or is in service.
bool on_st;

	/* B-WF2Q+ start and finish timestamps [sectors/weight] */

u64 start, finish;

	/* tree the entity is enqueued into; %NULL if not on a tree */
struct rb_root *tree;

         * minimum start time of the (active) subtree rooted at this
         * entity; used for O(log N) lookups into active trees
u64 min_start;

	/* amount of service received during the last service slot */
int service;

	/* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */
int budget;

	/* weight of the queue */
int weight;
	/* next weight if a change is in progress */
int new_weight;

	/* original weight, used to implement weight boosting */
int orig_weight;

	/* parent entity, for hierarchical scheduling */
struct bfq_entity *parent;

         * For non-leaf nodes in the hierarchy, the associated
         * scheduler queue, %NULL on leaf nodes.
struct bfq_sched_data *my_sched_data;
	/* the scheduler queue this entity belongs to */
struct bfq_sched_data *sched_data;

	/* flag, set to request a weight, ioprio or ioprio_class change  */
int prio_changed;

struct bfq_group;

 * struct bfq_ttime - per process thinktime stats.

struct bfq_ttime {
	/* completion time of the last request */
u64 last_end_request;

	/* total process thinktime */
u64 ttime_total;
	/* number of thinktime samples */
unsigned long ttime_samples;
	/* average process thinktime */
u64 ttime_mean;

 * struct bfq_queue - leaf schedulable entity.
 * A bfq_queue is a leaf request queue; it can be associated with an
 * io_context or more, if it  is  async or shared  between  cooperating
 * processes. @cgroup holds a reference to the cgroup, to be sure that it
 * does not disappear while a bfqq still references it (mostly to avoid
 * races between request issuing and task migration followed by cgroup
 * destruction).
 * All the fields are protected by the queue lock of the containing bfqd.

struct bfq_queue {
	/* reference counter */
int ref;
	/* parent bfq_data */
struct bfq_data *bfqd;

	/* current ioprio and ioprio class */

unsigned short ioprio, ioprio_class;
	/* next ioprio and ioprio class if a change is in progress */

unsigned short new_ioprio, new_ioprio_class;

         * Shared bfq_queue if queue is cooperating with one or more
         * other queues.
struct bfq_queue *new_bfqq;
	/* request-position tree member (see bfq_group's @rq_pos_tree) */
struct rb_node pos_node;
	/* request-position tree root (see bfq_group's @rq_pos_tree) */
struct rb_root *pos_root;

	/* sorted list of pending requests */
struct rb_root sort_list;
	/* if fifo isn't expired, next request to serve */
struct request *next_rq;
	/* number of sync and async requests queued */
int queued[2];
	/* number of requests currently allocated */
int allocated;
	/* number of pending metadata requests */
int meta_pending;
	/* fifo list of requests in sort_list */
struct list_head fifo;

	/* entity representing this queue in the scheduler */
struct bfq_entity entity;

	/* maximum budget allowed from the feedback mechanism */
int max_budget;
	/* budget expiration (in jiffies) */
unsigned long budget_timeout;

	/* number of requests on the dispatch list or inside driver */
int dispatched;

	/* status flags */
unsigned long flags;

	/* node for active/idle bfqq list inside parent bfqd */
struct list_head bfqq_list;

	/* associated @bfq_ttime struct */
struct bfq_ttime ttime;

	/* bit vector: a 1 for each seeky requests in history */
u32 seek_history;

	/* node for the device's burst list */
struct hlist_node burst_list_node;

	/* position of the last request enqueued */
sector_t last_request_pos;

	/* Number of consecutive pairs of request completion and
         * arrival, such that the queue becomes idle after the
         * completion, but the next request arrives within an idle
         * time slice; used only if the queue's IO_bound flag has been
         * cleared.
unsigned int requests_within_timer;

	/* pid of the process owning the queue, used for logging purposes */
pid_t pid;

         * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL
         * if the queue is shared.
struct bfq_io_cq *bic;

	/* current maximum weight-raising time for this queue */
unsigned long wr_cur_max_time;
         * Minimum time instant such that, only if a new request is
         * enqueued after this time instant in an idle @bfq_queue with
         * no outstanding requests, then the task associated with the
         * queue it is deemed as soft real-time (see the comments on
         * the function bfq_bfqq_softrt_next_start())
unsigned long soft_rt_next_start;
         * Start time of the current weight-raising period if
         * the @bfq-queue is being weight-raised, otherwise
         * finish time of the last weight-raising period.
unsigned long last_wr_start_finish;
	/* factor by which the weight of this queue is multiplied */
unsigned int wr_coeff;
         * Time of the last transition of the @bfq_queue from idle to
         * backlogged.
unsigned long last_idle_bklogged;
         * Cumulative service received from the @bfq_queue since the
         * last transition from idle to backlogged.
unsigned long service_from_backlogged;

         * Value of wr start time when switching to soft rt
unsigned long wr_start_at_switch_to_srt;

unsigned long split_time; /* time of last split */

 * struct bfq_io_cq - per (request_queue, io_context) structure.

struct bfq_io_cq {
	/* associated io_cq structure */
struct io_cq icq; /* must be the first member */
	/* array of two process queues, the sync and the async */
struct bfq_queue *bfqq[2];
	/* per (request_queue, blkcg) ioprio */
int ioprio;
uint64_t blkcg_serial_nr; /* the current blkcg serial */
         * Snapshot of the idle window before merging; taken to
         * remember this value while the queue is merged, so as to be
         * able to restore it in case of split.
bool saved_idle_window;
         * Same purpose as the previous two fields for the I/O bound
         * classification of a queue.
bool saved_IO_bound;

         * Same purpose as the previous fields for the value of the
         * field keeping the queue's belonging to a large burst
bool saved_in_large_burst;
         * True if the queue belonged to a burst list before its merge
         * with another cooperating queue.
bool was_in_burst_list;

         * Similar to previous fields: save wr information.
unsigned long saved_wr_coeff;
unsigned long saved_last_wr_start_finish;
unsigned long saved_wr_start_at_switch_to_srt;
unsigned int saved_wr_cur_max_time;
struct bfq_ttime saved_ttime;

enum bfq_device_speed {

 * struct bfq_data - per-device data structure.
 * All the fields are protected by @lock.

struct bfq_data {
	/* device request queue */
struct request_queue *queue;
	/* dispatch queue */
struct list_head dispatch;

	/* root bfq_group for the device */
struct bfq_group *root_group;

         * rbtree of weight counters of @bfq_queues, sorted by
         * weight. Used to keep track of whether all @bfq_queues have
         * the same weight. The tree contains one counter for each
         * distinct weight associated to some active and not
         * weight-raised @bfq_queue (see the comments to the functions
         * bfq_weights_tree_[add|remove] for further details).
struct rb_root queue_weights_tree;
         * rbtree of non-queue @bfq_entity weight counters, sorted by
         * weight. Used to keep track of whether all @bfq_groups have
         * the same weight. The tree contains one counter for each
         * distinct weight associated to some active @bfq_group (see
         * the comments to the functions bfq_weights_tree_[add|remove]
         * for further details).
struct rb_root group_weights_tree;

         * Number of bfq_queues containing requests (including the
         * queue in service, even if it is idling).
int busy_queues;
	/* number of weight-raised busy @bfq_queues */
int wr_busy_queues;
	/* number of queued requests */
int queued;
	/* number of requests dispatched and waiting for completion */
int rq_in_driver;

         * Maximum number of requests in driver in the last
         * @hw_tag_samples completed requests.
int max_rq_in_driver;
	/* number of samples used to calculate hw_tag */
int hw_tag_samples;
	/* flag set to one if the driver is showing a queueing behavior */
int hw_tag;

	/* number of budgets assigned */
int budgets_assigned;

         * Timer set when idling (waiting) for the next request from
         * the queue in service.
struct hrtimer idle_slice_timer;

	/* bfq_queue in service */
struct bfq_queue *in_service_queue;

	/* on-disk position of the last served request */
sector_t last_position;

	/* time of last request completion (ns) */
u64 last_completion;

	/* time of first rq dispatch in current observation interval (ns) */
u64 first_dispatch;
	/* time of last rq dispatch in current observation interval (ns) */
u64 last_dispatch;

	/* beginning of the last budget */
ktime_t last_budget_start;
	/* beginning of the last idle slice */
ktime_t last_idling_start;

	/* number of samples in current observation interval */
int peak_rate_samples;
	/* num of samples of seq dispatches in current observation interval */
u32 sequential_samples;
	/* total num of sectors transferred in current observation interval */
u64 tot_sectors_dispatched;
	/* max rq size seen during current observation interval (sectors) */
u32 last_rq_max_size;
	/* time elapsed from first dispatch in current observ. interval (us) */
u64 delta_from_first;
         * Current estimate of the device peak rate, measured in
         * [BFQ_RATE_SHIFT * sectors/usec]. The left-shift by
         * BFQ_RATE_SHIFT is performed to increase precision in
         * fixed-point calculations.
u32 peak_rate;

	/* maximum budget allotted to a bfq_queue before rescheduling */
int bfq_max_budget;

	/* list of all the bfq_queues active on the device */
struct list_head active_list;
	/* list of all the bfq_queues idle on the device */
struct list_head idle_list;

         * Timeout for async/sync requests; when it fires, requests
         * are served in fifo order.
u64 bfq_fifo_expire[2];
	/* weight of backward seeks wrt forward ones */
unsigned int bfq_back_penalty;
	/* maximum allowed backward seek */
unsigned int bfq_back_max;
	/* maximum idling time */
u32 bfq_slice_idle;

	/* user-configured max budget value (0 for auto-tuning) */
int bfq_user_max_budget;
         * Timeout for bfq_queues to consume their budget; used to
         * prevent seeky queues from imposing long latencies to
         * sequential or quasi-sequential ones (this also implies that
         * seeky queues cannot receive guarantees in the service
         * domain; after a timeout they are charged for the time they
         * have been in service, to preserve fairness among them, but
         * without service-domain guarantees).
unsigned int bfq_timeout;

         * Number of consecutive requests that must be issued within
         * the idle time slice to set again idling to a queue which
         * was marked as non-I/O-bound (see the definition of the
         * IO_bound flag for further details).
unsigned int bfq_requests_within_timer;

         * Force device idling whenever needed to provide accurate
         * service guarantees, without caring about throughput
         * issues. CAVEAT: this may even increase latencies, in case
         * of useless idling for processes that did stop doing I/O.
bool strict_guarantees;

         * Last time at which a queue entered the current burst of
         * queues being activated shortly after each other; for more
         * details about this and the following parameters related to
         * a burst of activations, see the comments on the function
         * bfq_handle_burst.
unsigned long last_ins_in_burst;
         * Reference time interval used to decide whether a queue has
         * been activated shortly after @last_ins_in_burst.
unsigned long bfq_burst_interval;
	/* number of queues in the current burst of queue activations */
int burst_size;

	/* common parent entity for the queues in the burst */
struct bfq_entity *burst_parent_entity;
	/* Maximum burst size above which the current queue-activation
         * burst is deemed as 'large'.
unsigned long bfq_large_burst_thresh;
	/* true if a large queue-activation burst is in progress */
bool large_burst;
         * Head of the burst list (as for the above fields, more
         * details in the comments on the function bfq_handle_burst).
struct hlist_head burst_list;

	/* if set to true, low-latency heuristics are enabled */
bool low_latency;
         * Maximum factor by which the weight of a weight-raised queue
         * is multiplied.
unsigned int bfq_wr_coeff;
	/* maximum duration of a weight-raising period (jiffies) */
unsigned int bfq_wr_max_time;

	/* Maximum weight-raising duration for soft real-time processes */
unsigned int bfq_wr_rt_max_time;
         * Minimum idle period after which weight-raising may be
         * reactivated for a queue (in jiffies).
unsigned int bfq_wr_min_idle_time;
         * Minimum period between request arrivals after which
         * weight-raising may be reactivated for an already busy async
         * queue (in jiffies).
unsigned long bfq_wr_min_inter_arr_async;

	/* Max service-rate for a soft real-time queue, in sectors/sec */
unsigned int bfq_wr_max_softrt_rate;
         * Cached value of the product R*T, used for computing the
         * maximum duration of weight raising automatically.
u64 RT_prod;
	/* device-speed class for the low-latency heuristic */
enum bfq_device_speed device_speed;

	/* fallback dummy bfqq for extreme OOM conditions */
struct bfq_queue oom_bfqq;

spinlock_t lock;

         * bic associated with the task issuing current bio for
         * merging. This and the next field are used as a support to
         * be able to perform the bic lookup, needed by bio-merge
         * functions, before the scheduler lock is taken, and thus
         * avoid taking the request-queue lock while the scheduler
         * lock is being held.
struct bfq_io_cq *bio_bic;
	/* bfqq associated with the task issuing current bio for merging */
struct bfq_queue *bio_bfqq;

enum bfqq_state_flags {
BFQQF_just_created = 0,	/* queue just allocated */
BFQQF_busy,		/* has requests or is in service */
BFQQF_wait_request,	/* waiting for a request */
BFQQF_non_blocking_wait_rq, /*
                                     * waiting for a request
                                     * without idling the device
BFQQF_fifo_expire,	/* FIFO checked in this slice */
BFQQF_idle_window,	/* slice idling enabled */
BFQQF_sync,		/* synchronous queue */
BFQQF_IO_bound,		/*
                                 * bfqq has timed-out at least once
                                 * having consumed at most 2/10 of
                                 * its budget
BFQQF_in_large_burst,	/*
                                 * bfqq activated in a large burst,
                                 * see comments to bfq_handle_burst.
BFQQF_softrt_update,	/*
                                 * may need softrt-next-start
                                 * update
BFQQF_coop,		/* bfqq is shared */
BFQQF_split_coop	/* shared bfqq will be split */

#define BFQ_BFQQ_FNS(name)						\
void bfq_mark_bfqq_##name(struct bfq_queue *bfqq);                      \
void bfq_clear_bfqq_##name(struct bfq_queue *bfqq);                     \
int bfq_bfqq_##name(const struct bfq_queue *bfqq);














/* Expiration reasons. */

enum bfqq_expiration {
                                         * queue has been idling for
                                         * too long
BFQQE_BUDGET_TIMEOUT,	/* budget took too long to be used */
BFQQE_BUDGET_EXHAUSTED,	/* budget consumed */
BFQQE_NO_MORE_REQUESTS,	/* the queue has no more requests */
BFQQE_PREEMPTED		/* preemption in progress */

struct bfqg_stats {
	/* number of ios merged */
struct blkg_rwstat		merged;
	/* total time spent on device in ns, may not be accurate w/ queueing */
struct blkg_rwstat		service_time;
	/* total time spent waiting in scheduler queue in ns */
struct blkg_rwstat		wait_time;
	/* number of IOs queued up */
struct blkg_rwstat		queued;
	/* total disk time and nr sectors dispatched by this group */
struct blkg_stat		time;
	/* sum of number of ios queued across all samples */
struct blkg_stat		avg_queue_size_sum;
	/* count of samples taken for average */
struct blkg_stat		avg_queue_size_samples;
	/* how many times this group has been removed from service tree */
struct blkg_stat		dequeue;
	/* total time spent waiting for it to be assigned a timeslice. */
struct blkg_stat		group_wait_time;
	/* time spent idling for this blkcg_gq */
struct blkg_stat		idle_time;
	/* total time with empty current active q with other requests queued */
struct blkg_stat		empty_time;
	/* fields after this shouldn't be cleared on stat reset */
uint64_t			start_group_wait_time;
uint64_t			start_idle_time;
uint64_t			start_empty_time;
uint16_t			flags;


 * struct bfq_group_data - per-blkcg storage for the blkio subsystem.
 * @ps: @blkcg_policy_storage that this structure inherits
 * @weight: weight of the bfq_group

struct bfq_group_data {
	/* must be the first member */
struct blkcg_policy_data pd;

unsigned int weight;

 * struct bfq_group - per (device, cgroup) data structure.
 * @entity: schedulable entity to insert into the parent group sched_data.
 * @sched_data: own sched_data, to contain child entities (they may be
 *              both bfq_queues and bfq_groups).
 * @bfqd: the bfq_data for the device this group acts upon.
 * @async_bfqq: array of async queues for all the tasks belonging to
 *              the group, one queue per ioprio value per ioprio_class,
 *              except for the idle class that has only one queue.
 * @async_idle_bfqq: async queue for the idle class (ioprio is ignored).
 * @my_entity: pointer to @entity, %NULL for the toplevel group; used
 *             to avoid too many special cases during group creation/
 *             migration.
 * @stats: stats for this bfqg.
 * @active_entities: number of active entities belonging to the group;
 *                   unused for the root group. Used to know whether there
 *                   are groups with more than one active @bfq_entity
 *                   (see the comments to the function
 *                   bfq_bfqq_may_idle()).
 * @rq_pos_tree: rbtree sorted by next_request position, used when
 *               determining if two or more queues have interleaving
 *               requests (see bfq_find_close_cooperator()).
 * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup
 * there is a set of bfq_groups, each one collecting the lower-level
 * entities belonging to the group that are acting on the same device.
 * Locking works as follows:
 *    o @bfqd is protected by the queue lock, RCU is used to access it
 *      from the readers.
 *    o All the other fields are protected by the @bfqd queue lock.

struct bfq_group {
	/* must be the first member */
struct blkg_policy_data pd;

	/* cached path for this blkg (see comments in bfq_bic_update_cgroup) */
char blkg_path[128];

	/* reference counter (see comments in bfq_bic_update_cgroup) */
int ref;

struct bfq_entity entity;
struct bfq_sched_data sched_data;

void *bfqd;

struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
struct bfq_queue *async_idle_bfqq;

struct bfq_entity *my_entity;

int active_entities;

struct rb_root rq_pos_tree;

struct bfqg_stats stats;


struct bfq_group {
struct bfq_sched_data sched_data;

struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
struct bfq_queue *async_idle_bfqq;

struct rb_root rq_pos_tree;

struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);

/* --------------- main algorithm interface ----------------- */

#define BFQ_SERVICE_TREE_INIT	((struct bfq_service_tree)              \
                                { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })

extern const int bfq_timeout;

struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync);
void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, bool is_sync);
struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic);
void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq);
void bfq_weights_tree_add(struct bfq_data *bfqd, struct bfq_entity *entity,
			  struct rb_root *root);
void bfq_weights_tree_remove(struct bfq_data *bfqd, struct bfq_entity *entity,
			     struct rb_root *root);
void bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq,
		     bool compensate, enum bfqq_expiration reason);
void bfq_put_queue(struct bfq_queue *bfqq);
void bfq_end_wr_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
void bfq_schedule_dispatch(struct bfq_data *bfqd);
void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);

/* ------------ end of main algorithm interface -------------- */

/* ---------------- cgroups-support interface ---------------- */

void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
			      unsigned int op);
void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op);
void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op);
void bfqg_stats_update_completion(struct bfq_group *bfqg, uint64_t start_time,
				  uint64_t io_start_time, unsigned int op);
void bfqg_stats_update_dequeue(struct bfq_group *bfqg);
void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg);
void bfqg_stats_update_idle_time(struct bfq_group *bfqg);
void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg);
void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg);
void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
		   struct bfq_group *bfqg);

void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg);
void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio);
void bfq_end_wr_async(struct bfq_data *bfqd);
struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
				     struct blkcg *blkcg);
struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node);
void bfqg_and_blkg_put(struct bfq_group *bfqg);

extern struct cftype bfq_blkcg_legacy_files[];
extern struct cftype bfq_blkg_files[];
extern struct blkcg_policy blkcg_policy_bfq;

/* ------------- end of cgroups-support interface ------------- */

/* - interface of the internal hierarchical B-WF2Q+ scheduler - */

/* both next loops stop at one of the child entities of the root group */

#define for_each_entity(entity)	\
	for (; entity ; entity = entity->parent)

 * For each iteration, compute parent in advance, so as to be safe if
 * entity is deallocated during the iteration. Such a deallocation may
 * happen as a consequence of a bfq_put_queue that frees the bfq_queue
 * containing entity.

#define for_each_entity_safe(entity, parent) \
	for (; entity && ({ parent = entity->parent; 1; }); entity = parent)

 * Next two macros are fake loops when cgroups support is not
 * enabled. I fact, in such a case, there is only one level to go up
 * (to reach the root group).

#define for_each_entity(entity)	\
	for (; entity ; entity = NULL)

#define for_each_entity_safe(entity, parent) \
	for (parent = NULL; entity ; entity = parent)

struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq);
struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
struct bfq_service_tree *bfq_entity_service_tree(struct bfq_entity *entity);
struct bfq_entity *bfq_entity_of(struct rb_node *node);
unsigned short bfq_ioprio_to_weight(int ioprio);
void bfq_put_idle_entity(struct bfq_service_tree *st,
			 struct bfq_entity *entity);
struct bfq_service_tree *
__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
				struct bfq_entity *entity);
void bfq_bfqq_served(struct bfq_queue *bfqq, int served);
void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq,
			  unsigned long time_ms);
bool __bfq_deactivate_entity(struct bfq_entity *entity,
			     bool ins_into_idle_tree);
bool next_queue_may_preempt(struct bfq_data *bfqd);
struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd);
void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd);
void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
			 bool ins_into_idle_tree, bool expiration);
void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
		       bool expiration);
void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq);

/* --------------- end of interface of B-WF2Q+ ---------------- */

/* Logging facilities. */
struct bfq_group *bfqq_group(struct bfq_queue *bfqq);

#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	do {                    \
        blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s " fmt, (bfqq)->pid,\
                        bfq_bfqq_sync((bfqq)) ? 'S' : 'A',              \
                        bfqq_group(bfqq)->blkg_path, ##args);           \
} while (0)

#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	\
	blk_add_trace_msg((bfqd)->queue, "%s " fmt, (bfqg)->blkg_path, ##args)


#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	\
	blk_add_trace_msg((bfqd)->queue, "bfq%d%c " fmt, (bfqq)->pid,   \
                        bfq_bfqq_sync((bfqq)) ? 'S' : 'A',              \

#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)		do {} while (0)


#define bfq_log(bfqd, fmt, args...) \
	blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)

#endif /* _BFQ_H */

Overall Contributors

Paolo Valente192899.38%266.67%
Jens Axboe120.62%133.33%
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