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Diffstat (limited to 'block/bfq-iosched.h')
| -rw-r--r-- | block/bfq-iosched.h | 1210 |
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diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h new file mode 100644 index 0000000000..467e8cfc41 --- /dev/null +++ b/block/bfq-iosched.h @@ -0,0 +1,1210 @@ +/* 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 "blk-cgroup-rwstat.h" + +#define BFQ_IOPRIO_CLASSES 3 +#define BFQ_CL_IDLE_TIMEOUT (HZ/5) + +#define BFQ_MIN_WEIGHT 1 +#define BFQ_MAX_WEIGHT 1000 +#define BFQ_WEIGHT_CONVERSION_COEFF 10 + +#define BFQ_DEFAULT_QUEUE_IOPRIO 4 + +#define BFQ_DEFAULT_GRP_IOPRIO 0 +#define BFQ_DEFAULT_GRP_CLASS IOPRIO_CLASS_BE + +#define MAX_BFQQ_NAME_LENGTH 16 + +/* + * 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. + */ +#define BFQ_SOFTRT_WEIGHT_FACTOR 100 + +/* + * Maximum number of actuators supported. This constant is used simply + * to define the size of the static array that will contain + * per-actuator data. The current value is hopefully a good upper + * bound to the possible number of actuators of any actual drive. + */ +#define BFQ_MAX_ACTUATORS 8 + +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 + * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE. + * 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; + + /* Number of requests allocated in the subtree of this entity */ + int allocated; + + /* 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; + +#ifdef CONFIG_BFQ_GROUP_IOSCHED + /* flag, set if the entity is counted in groups_with_pending_reqs */ + bool in_groups_with_pending_reqs; +#endif + + /* 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. Besides, it contains I/O requests for only one actuator + * (an io_context is associated with a different bfq_queue for each + * actuator it generates I/O for). @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 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 */ + + /* + * 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; + /* time when we started considering this waker */ + u64 waker_detection_started; + + /* 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; + + /* index of the actuator this queue is associated with */ + unsigned int actuator_idx; +}; + +/** +* struct bfq_data - bfqq data unique and persistent for associated bfq_io_cq +*/ +struct bfq_iocq_bfqq_data { + /* + * Snapshot of the has_short_time flag before merging; taken + * to remember its values 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 values 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_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 */ + /* + * Matrix of associated process queues: first row for async + * queues, second row sync queues. Each row contains one + * column for each actuator. An I/O request generated by the + * process is inserted into the queue pointed by bfqq[i][j] if + * the request is to be served by the j-th actuator of the + * drive, where i==0 or i==1, depending on whether the request + * is async or sync. So there is a distinct queue for each + * actuator. + */ + struct bfq_queue *bfqq[2][BFQ_MAX_ACTUATORS]; + /* per (request_queue, blkcg) ioprio */ + int ioprio; +#ifdef CONFIG_BFQ_GROUP_IOSCHED + uint64_t blkcg_serial_nr; /* the current blkcg serial */ +#endif + + /* + * Persistent data for associated synchronous process queues + * (one queue per actuator, see field bfqq above). In + * particular, each of these queues may undergo a merge. + */ + struct bfq_iocq_bfqq_data bfqq_data[BFQ_MAX_ACTUATORS]; + + unsigned int requests; /* Number of requests this process has in flight */ +}; + +/** + * 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; + +#ifdef CONFIG_BFQ_GROUP_IOSCHED + /* + * Number of groups with at least one 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 + * 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 processes. Consider a group + * that is inactive, i.e., that has no 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 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 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 + * 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 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 queue of the entity remains + * with no request waiting for completion. + */ + unsigned int num_groups_with_pending_reqs; +#endif + + /* + * 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 tot_rq_in_driver; + /* + * number of requests dispatched and waiting for completion + * for each actuator + */ + int rq_in_driver[BFQ_MAX_ACTUATORS]; + + /* 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 for a specific actuator + * on the device. Keeping active queues separate on a + * per-actuator basis helps implementing per-actuator + * injection more efficiently. + */ + struct list_head active_list[BFQ_MAX_ACTUATORS]; + /* 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 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]; + unsigned int full_depth_shift; + + /* + * Number of independent actuators. This is equal to 1 in + * case of single-actuator drives. + */ + unsigned int num_actuators; + /* + * Disk independent access ranges for each actuator + * in this device. + */ + sector_t sector[BFQ_MAX_ACTUATORS]; + sector_t nr_sectors[BFQ_MAX_ACTUATORS]; + struct blk_independent_access_range ia_ranges[BFQ_MAX_ACTUATORS]; + + /* + * If the number of I/O requests queued in the device for a + * given actuator is below next threshold, then the actuator + * is deemed as underutilized. If this condition is found to + * hold for some actuator upon a dispatch, but (i) the + * in-service queue does not contain I/O for that actuator, + * while (ii) some other queue does contain I/O for that + * actuator, then the head I/O request of the latter queue is + * returned (injected), instead of the head request of the + * currently in-service queue. + * + * We set the threshold, empirically, to the minimum possible + * value for which an actuator is fully utilized, or close to + * be fully utilized. By doing so, injected I/O 'steals' as + * few drive-queue slots as possibile to the in-service + * queue. This reduces as much as possible the probability + * that the service of I/O from the in-service bfq_queue gets + * delayed because of slot exhaustion, i.e., because all the + * slots of the drive queue are filled with I/O injected from + * other queues (NCQ provides for 32 slots). + */ + unsigned int actuator_load_threshold; +}; + +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); + +BFQ_BFQQ_FNS(just_created); +BFQ_BFQQ_FNS(busy); +BFQ_BFQQ_FNS(wait_request); +BFQ_BFQQ_FNS(non_blocking_wait_rq); +BFQ_BFQQ_FNS(fifo_expire); +BFQ_BFQQ_FNS(has_short_ttime); +BFQ_BFQQ_FNS(sync); +BFQ_BFQQ_FNS(IO_bound); +BFQ_BFQQ_FNS(in_large_burst); +BFQ_BFQQ_FNS(coop); +BFQ_BFQQ_FNS(split_coop); +BFQ_BFQQ_FNS(softrt_update); +#undef BFQ_BFQQ_FNS + +/* Expiration reasons. */ +enum bfqq_expiration { + BFQQE_TOO_IDLE = 0, /* + * 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; +#ifdef CONFIG_BFQ_CGROUP_DEBUG + /* 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; +#endif /* CONFIG_BFQ_CGROUP_DEBUG */ +}; + +#ifdef CONFIG_BFQ_GROUP_IOSCHED + +/* + * 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) */ + refcount_t ref; + + struct bfq_entity entity; + struct bfq_sched_data sched_data; + + struct bfq_data *bfqd; + + struct bfq_queue *async_bfqq[2][IOPRIO_NR_LEVELS][BFQ_MAX_ACTUATORS]; + struct bfq_queue *async_idle_bfqq[BFQ_MAX_ACTUATORS]; + + struct bfq_entity *my_entity; + + int active_entities; + int num_queues_with_pending_reqs; + + struct rb_root rq_pos_tree; + + struct bfqg_stats stats; +}; + +#else +struct bfq_group { + struct bfq_entity entity; + struct bfq_sched_data sched_data; + + struct bfq_queue *async_bfqq[2][IOPRIO_NR_LEVELS][BFQ_MAX_ACTUATORS]; + struct bfq_queue *async_idle_bfqq[BFQ_MAX_ACTUATORS]; + + struct rb_root rq_pos_tree; +}; +#endif + +/* --------------- 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, + unsigned int actuator_idx); +void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, bool is_sync, + unsigned int actuator_idx); +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_queue *bfqq); +void bfq_weights_tree_remove(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_put_cooperator(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_remove(struct bfq_group *bfqg, blk_opf_t opf); +void bfqg_stats_update_io_merged(struct bfq_group *bfqg, blk_opf_t opf); +void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns, + u64 io_start_time_ns, blk_opf_t opf); +void bfqg_stats_update_dequeue(struct bfq_group *bfqg); +void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg); +void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, + struct bfq_group *bfqg); + +#ifdef CONFIG_BFQ_CGROUP_DEBUG +void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq, + blk_opf_t opf); +void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg); +void bfqg_stats_update_idle_time(struct bfq_group *bfqg); +void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg); +#endif + +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_bio_bfqg(struct bfq_data *bfqd, struct bio *bio); +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); + +#ifdef CONFIG_BFQ_GROUP_IOSCHED +extern struct cftype bfq_blkcg_legacy_files[]; +extern struct cftype bfq_blkg_files[]; +extern struct blkcg_policy blkcg_policy_bfq; +#endif + +/* ------------- end of cgroups-support interface ------------- */ + +/* - interface of the internal hierarchical B-WF2Q+ scheduler - */ + +#ifdef CONFIG_BFQ_GROUP_IOSCHED +/* 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) + +#else /* CONFIG_BFQ_GROUP_IOSCHED */ +/* + * 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) +#endif /* CONFIG_BFQ_GROUP_IOSCHED */ + +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_queue *bfqq, bool expiration); +void bfq_add_bfqq_busy(struct bfq_queue *bfqq); +void bfq_add_bfqq_in_groups_with_pending_reqs(struct bfq_queue *bfqq); +void bfq_del_bfqq_in_groups_with_pending_reqs(struct bfq_queue *bfqq); + +/* --------------- end of interface of B-WF2Q+ ---------------- */ + +/* Logging facilities. */ +static inline void bfq_bfqq_name(struct bfq_queue *bfqq, char *str, int len) +{ + char type = bfq_bfqq_sync(bfqq) ? 'S' : 'A'; + + if (bfqq->pid != -1) + snprintf(str, len, "bfq%d%c", bfqq->pid, type); + else + snprintf(str, len, "bfqSHARED-%c", type); +} + +#ifdef CONFIG_BFQ_GROUP_IOSCHED +struct bfq_group *bfqq_group(struct bfq_queue *bfqq); + +#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \ + char pid_str[MAX_BFQQ_NAME_LENGTH]; \ + if (likely(!blk_trace_note_message_enabled((bfqd)->queue))) \ + break; \ + bfq_bfqq_name((bfqq), pid_str, MAX_BFQQ_NAME_LENGTH); \ + blk_add_cgroup_trace_msg((bfqd)->queue, \ + &bfqg_to_blkg(bfqq_group(bfqq))->blkcg->css, \ + "%s " fmt, pid_str, ##args); \ +} while (0) + +#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do { \ + blk_add_cgroup_trace_msg((bfqd)->queue, \ + &bfqg_to_blkg(bfqg)->blkcg->css, fmt, ##args); \ +} while (0) + +#else /* CONFIG_BFQ_GROUP_IOSCHED */ + +#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \ + char pid_str[MAX_BFQQ_NAME_LENGTH]; \ + if (likely(!blk_trace_note_message_enabled((bfqd)->queue))) \ + break; \ + bfq_bfqq_name((bfqq), pid_str, MAX_BFQQ_NAME_LENGTH); \ + blk_add_trace_msg((bfqd)->queue, "%s " fmt, pid_str, ##args); \ +} while (0) +#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do {} while (0) + +#endif /* CONFIG_BFQ_GROUP_IOSCHED */ + +#define bfq_log(bfqd, fmt, args...) \ + blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args) + +#endif /* _BFQ_H */ |