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/* SPDX-License-Identifier: GPL-2.0-or-later */
* Header file for the BFQ I/O scheduler: data structures and
* prototypes of interface functions among BFQ components.
#ifndef _BFQ_H
#define _BFQ_H
#include <linux/blktrace_api.h>
#include <linux/hrtimer.h>
#include <linux/blk-cgroup.h>
#include "blk-cgroup-rwstat.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 in a hierarchical setup.
* 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+.
* The schedule is implemented by the service trees, plus the field
* @next_in_service, which points to the entity on the active trees
* that will be served next, if 1) no changes in the schedule occurs
* before the current in-service entity is expired, 2) the in-service
* queue becomes idle when it expires, and 3) if the entity pointed by
* in_service_entity is not a queue, then the in-service child entity
* of the entity pointed by in_service_entity becomes idle on
* expiration. This peculiar definition allows for the following
* optimization, not yet exploited: while a given entity is still in
* service, we already know which is the best candidate for next
* service among the other active entities in the same parent
* entity. We can then quickly compare the timestamps of the
* in-service entity with those of such best candidate.
* All fields are protected by the 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 queues
* with a given weight.
struct bfq_weight_counter {
unsigned int weight; /* weight of the queues this counter refers to */
unsigned int num_active; /* nr of active queues with this weight */
* Weights tree member (see bfq_data's @queue_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;
* 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_or_in_serv;
/* 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;
/* device weight, if non-zero, it overrides the default weight of
* bfq_group_data */
int dev_weight;
/* 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;
/* flag, set if the entity is counted in groups_with_pending_reqs */
bool in_groups_with_pending_reqs;
/* last child queue of entity created (for non-leaf entities) */
struct bfq_queue *last_bfqq_created;
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;
/* counter of references from other queues for delayed stable merge */
int stable_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;
/* last total-service-time sample, see bfq_update_inject_limit() */
u64 last_serv_time_ns;
/* limit for request injection */
unsigned int inject_limit;
/* last time the inject limit has been decreased, in jiffies */
unsigned long decrease_time_jif;
* 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;
/* pointer to the weight counter associated with this entity */
struct bfq_weight_counter *weight_counter;
/* 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;
/* when bfqq started to do I/O within the last observation window */
u64 io_start_time;
/* how long bfqq has remained empty during the last observ. window */
u64 tot_idle_time;
/* 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;
* Cumulative service received from the @bfq_queue since its
* last transition to weight-raised state.
unsigned long service_from_wr;
* 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 */
unsigned long first_IO_time; /* time of first I/O for this queue */
unsigned long creation_time; /* when this queue is created */
/* max service rate measured so far */
u32 max_service_rate;
* Pointer to the waker queue for this queue, i.e., to the
* queue Q such that this queue happens to get new I/O right
* after some I/O request of Q is completed. For details, see
* the comments on the choice of the queue for injection in
* bfq_select_queue().
struct bfq_queue *waker_bfqq;
/* pointer to the curr. tentative waker queue, see bfq_check_waker() */
struct bfq_queue *tentative_waker_bfqq;
/* number of times the same tentative waker has been detected */
unsigned int num_waker_detections;
/* node for woken_list, see below */
struct hlist_node woken_list_node;
* Head of the list of the woken queues for this queue, i.e.,
* of the list of the queues for which this queue is a waker
* queue. This list is used to reset the waker_bfqq pointer in
* the woken queues when this queue exits.
struct hlist_head woken_list;
* 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 has_short_time flag before merging; taken
* to remember its value while the queue is merged, so as to
* be able to restore it in case of split.
bool saved_has_short_ttime;
* Same purpose as the previous two fields for the I/O bound
* classification of a queue.
bool saved_IO_bound;
u64 saved_io_start_time;
u64 saved_tot_idle_time;
* 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;
* Save the weight when a merge occurs, to be able
* to restore it in case of split. If the weight is not
* correctly resumed when the queue is recycled,
* then the weight of the recycled queue could differ
* from the weight of the original queue.
unsigned int saved_weight;
* Similar to previous fields: save wr information.
unsigned long saved_wr_coeff;
unsigned long saved_last_wr_start_finish;
unsigned long saved_service_from_wr;
unsigned long saved_wr_start_at_switch_to_srt;
unsigned int saved_wr_cur_max_time;
struct bfq_ttime saved_ttime;
/* Save also injection state */
u64 saved_last_serv_time_ns;
unsigned int saved_inject_limit;
unsigned long saved_decrease_time_jif;
/* candidate queue for a stable merge (due to close creation time) */
struct bfq_queue *stable_merge_bfqq;
bool stably_merged; /* non splittable if true */
* 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_cached queue_weights_tree;
* Number of groups with at least one descendant process that
* has at least one request waiting for completion. Note that
* this accounts for also requests already dispatched, but not
* yet completed. Therefore this number of groups may differ
* (be larger) than the number of active groups, as a group is
* considered active only if its corresponding entity has
* descendant queues with at least one request queued. This
* number is used to decide whether a scenario is symmetric.
* For a detailed explanation see comments on the computation
* of the variable asymmetric_scenario in the function
* bfq_better_to_idle().
* However, it is hard to compute this number exactly, for
* groups with multiple descendant processes. Consider a group
* that is inactive, i.e., that has no descendant process with
* pending I/O inside BFQ queues. Then suppose that
* num_groups_with_pending_reqs is still accounting for this
* group, because the group has descendant processes with some
* I/O request still in flight. num_groups_with_pending_reqs
* should be decremented when the in-flight request of the
* last descendant process is finally completed (assuming that
* nothing else has changed for the group in the meantime, in
* terms of composition of the group and active/inactive state of child
* groups and processes). To accomplish this, an additional
* pending-request counter must be added to entities, and must
* be updated correctly. To avoid this additional field and operations,
* we resort to the following tradeoff between simplicity and
* accuracy: for an inactive group that is still counted in
* num_groups_with_pending_reqs, we decrement
* num_groups_with_pending_reqs when the first descendant
* process of the group remains with no request waiting for
* completion.
* Even this simpler decrement strategy requires a little
* carefulness: to avoid multiple decrements, we flag a group,
* more precisely an entity representing a group, as still
* counted in num_groups_with_pending_reqs when it becomes
* inactive. Then, when the first descendant queue of the
* entity remains with no request waiting for completion,
* num_groups_with_pending_reqs is decremented, and this flag
* is reset. After this flag is reset for the entity,
* num_groups_with_pending_reqs won't be decremented any
* longer in case a new descendant queue of the entity remains
* with no request waiting for completion.
unsigned int num_groups_with_pending_reqs;
* Per-class (RT, BE, IDLE) number of bfq_queues containing
* requests (including the queue in service, even if it is
* idling).
unsigned int busy_queues[3];
/* 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;
/* true if the device is non rotational and performs queueing */
bool nonrot_with_queueing;
* 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;
/* position of the last served request for the in-service queue */
sector_t in_serv_last_pos;
/* time of last request completion (ns) */
u64 last_completion;
/* bfqq owning the last completed rq */
struct bfq_queue *last_completed_rq_bfqq;
/* last bfqq created, among those in the root group */
struct bfq_queue *last_bfqq_created;
/* time of last transition from empty to non-empty (ns) */
u64 last_empty_occupied_ns;
* Flag set to activate the sampling of the total service time
* of a just-arrived first I/O request (see
* bfq_update_inject_limit()). This will cause the setting of
* waited_rq when the request is finally dispatched.
bool wait_dispatch;
* If set, then bfq_update_inject_limit() is invoked when
* waited_rq is eventually completed.
struct request *waited_rq;
* True if some request has been injected during the last service hole.
bool rqs_injected;
/* 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;
unsigned long last_idling_start_jiffies;
/* 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
* [(sectors/usec) / 2^BFQ_RATE_SHIFT]. 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;
* 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 ref_rate*ref_wr_duration, used
* for computing the maximum duration of weight raising
* automatically.
u64 rate_dur_prod;
/* 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;
* Depth limits used in bfq_limit_depth (see comments on the
* function)
unsigned int word_depths[2][2];
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_has_short_ttime, /* queue has a short think time */
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 bfq_stat {
struct percpu_counter cpu_cnt;
atomic64_t aux_cnt;
struct bfqg_stats {
/* basic stats */
struct blkg_rwstat bytes;
struct blkg_rwstat ios;
/* 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 bfq_stat time;
/* sum of number of ios queued across all samples */
struct bfq_stat avg_queue_size_sum;
/* count of samples taken for average */
struct bfq_stat avg_queue_size_samples;
/* how many times this group has been removed from service tree */
struct bfq_stat dequeue;
/* total time spent waiting for it to be assigned a timeslice. */
struct bfq_stat group_wait_time;
/* time spent idling for this blkcg_gq */
struct bfq_stat idle_time;
/* total time with empty current active q with other requests queued */
struct bfq_stat empty_time;
/* fields after this shouldn't be cleared on stat reset */
u64 start_group_wait_time;
u64 start_idle_time;
u64 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_NR_LEVELS];
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_entity entity;
struct bfq_sched_data sched_data;
struct bfq_queue *async_bfqq[2][IOPRIO_NR_LEVELS];
struct bfq_queue *async_idle_bfqq;
struct rb_root rq_pos_tree;
/* --------------- main algorithm interface ----------------- */
#define BFQ_SERVICE_TREE_INIT ((struct bfq_service_tree) \
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_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq);
void bfq_weights_tree_add(struct bfq_data *bfqd, struct bfq_queue *bfqq,
struct rb_root_cached *root);
void __bfq_weights_tree_remove(struct bfq_data *bfqd,
struct bfq_queue *bfqq,
struct rb_root_cached *root);
void bfq_weights_tree_remove(struct bfq_data *bfqd,
struct bfq_queue *bfqq);
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_release_process_ref(struct bfq_data *bfqd, struct bfq_queue *bfqq);
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_legacy_io(struct request_queue *q, struct request *rq);
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, u64 start_time_ns,
u64 io_start_time_ns, 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);
unsigned int bfq_tot_busy_queues(struct bfq_data *bfqd);
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,
bool update_class_too);
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);
bool __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,
bool expiration);
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. */
static inline void bfq_pid_to_str(int pid, char *str, int len)
if (pid != -1)
snprintf(str, len, "%d", pid);
snprintf(str, len, "SHARED-");
struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \
char pid_str[MAX_PID_STR_LENGTH]; \
if (likely(!blk_trace_note_message_enabled((bfqd)->queue))) \
break; \
bfq_pid_to_str((bfqq)->pid, pid_str, MAX_PID_STR_LENGTH); \
blk_add_cgroup_trace_msg((bfqd)->queue, \
bfqg_to_blkg(bfqq_group(bfqq))->blkcg, \
"bfq%s%c " fmt, pid_str, \
bfq_bfqq_sync((bfqq)) ? 'S' : 'A', ##args); \
} while (0)
#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do { \
blk_add_cgroup_trace_msg((bfqd)->queue, \
bfqg_to_blkg(bfqg)->blkcg, fmt, ##args); \
} while (0)
#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \
char pid_str[MAX_PID_STR_LENGTH]; \
if (likely(!blk_trace_note_message_enabled((bfqd)->queue))) \
break; \
bfq_pid_to_str((bfqq)->pid, pid_str, MAX_PID_STR_LENGTH); \
blk_add_trace_msg((bfqd)->queue, "bfq%s%c " fmt, pid_str, \
bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \
##args); \
} while (0)
#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 */