/* * BFQ-v5 for 3.0: data structures and common functions prototypes. * * Based on ideas and code from CFQ: * Copyright (C) 2003 Jens Axboe * * Copyright (C) 2008 Fabio Checconi * Paolo Valente */ #ifndef _BFQ_H #define _BFQ_H #include #include #include #include #define BFQ_IOPRIO_CLASSES 3 #define BFQ_CL_IDLE_TIMEOUT HZ/5 #define BFQ_MIN_WEIGHT 1 #define BFQ_MAX_WEIGHT 1000 #define BFQ_DEFAULT_GRP_WEIGHT 10 #define BFQ_DEFAULT_GRP_IOPRIO 0 #define BFQ_DEFAULT_GRP_CLASS IOPRIO_CLASS_BE struct bfq_entity; /** * struct bfq_service_tree - per ioprio_class service tree. * @active: tree for active entities (i.e., those backlogged). * @idle: tree for idle entities (i.e., those not backlogged, with V <= F_i). * @first_idle: idle entity with minimum F_i. * @last_idle: idle entity with maximum F_i. * @vtime: scheduler virtual time. * @wsum: scheduler weight sum; active and idle entities contribute to it. * * 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 { struct rb_root active; struct rb_root idle; struct bfq_entity *first_idle; struct bfq_entity *last_idle; u64 vtime; unsigned long wsum; }; /** * struct bfq_sched_data - multi-class scheduler. * @active_entity: entity under service. * @next_active: head-of-the-line entity in the scheduler. * @service_tree: array of service trees, one per ioprio_class. * * 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_active points to the active entity of the sched_data service * trees that will be scheduled next. * * 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+. * All the fields are protected by the queue lock of the containing bfqd. */ struct bfq_sched_data { struct bfq_entity *active_entity; struct bfq_entity *next_active; struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES]; }; /** * struct bfq_entity - schedulable entity. * @rb_node: service_tree member. * @on_st: flag, true if the entity is on a tree (either the active or * the idle one of its service_tree). * @finish: B-WF2Q+ finish timestamp (aka F_i). * @start: B-WF2Q+ start timestamp (aka S_i). * @tree: tree the entity is enqueued into; %NULL if not on a tree. * @min_start: minimum start time of the (active) subtree rooted at * this entity; used for O(log N) lookups into active trees. * @service: service received during the last round of service. * @budget: budget used to calculate F_i; F_i = S_i + @budget / @weight. * @weight: weight of the queue * @parent: parent entity, for hierarchical scheduling. * @my_sched_data: for non-leaf nodes in the cgroup hierarchy, the * associated scheduler queue, %NULL on leaf nodes. * @sched_data: the scheduler queue this entity belongs to. * @ioprio: the ioprio in use. * @new_weight: when a weight change is requested, the new weight value. * @orig_weight: original weight, used to implement weight boosting * @new_ioprio: when an ioprio change is requested, the new ioprio value. * @ioprio_class: the ioprio_class in use. * @new_ioprio_class: when an ioprio_class change is requested, the new * ioprio_class value. * @ioprio_changed: flag, true when the user requested a weight, ioprio or * ioprio_class change. * * 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 @ioprio_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 { struct rb_node rb_node; int on_st; u64 finish; u64 start; struct rb_root *tree; u64 min_start; unsigned long service, budget; unsigned short weight, new_weight; unsigned short orig_weight; struct bfq_entity *parent; struct bfq_sched_data *my_sched_data; struct bfq_sched_data *sched_data; unsigned short ioprio, new_ioprio; unsigned short ioprio_class, new_ioprio_class; int ioprio_changed; }; struct bfq_group; /** * struct bfq_queue - leaf schedulable entity. * @ref: reference counter. * @bfqd: parent bfq_data. * @new_bfqq: shared bfq_queue if queue is cooperating with * one or more other queues. * @pos_node: request-position tree member (see bfq_data's @rq_pos_tree). * @pos_root: request-position tree root (see bfq_data's @rq_pos_tree). * @sort_list: sorted list of pending requests. * @next_rq: if fifo isn't expired, next request to serve. * @queued: nr of requests queued in @sort_list. * @allocated: currently allocated requests. * @meta_pending: pending metadata requests. * @fifo: fifo list of requests in sort_list. * @entity: entity representing this queue in the scheduler. * @max_budget: maximum budget allowed from the feedback mechanism. * @budget_timeout: budget expiration (in jiffies). * @dispatched: number of requests on the dispatch list or inside driver. * @org_ioprio: saved ioprio during boosted periods. * @org_ioprio_class: saved ioprio_class during boosted periods. * @flags: status flags. * @bfqq_list: node for active/idle bfqq list inside our bfqd. * @seek_samples: number of seeks sampled * @seek_total: sum of the distances of the seeks sampled * @seek_mean: mean seek distance * @last_request_pos: position of the last request enqueued * @pid: pid of the process owning the queue, used for logging purposes. * @last_rais_start_time: last (idle -> weight-raised) transition attempt * @raising_cur_max_time: current max raising time for this queue * * A bfq_queue is a leaf request queue; it can be associated to an io_context * or more (if it is an async one). @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 distruction). * All the fields are protected by the queue lock of the containing bfqd. */ struct bfq_queue { atomic_t ref; struct bfq_data *bfqd; /* fields for cooperating queues handling */ struct bfq_queue *new_bfqq; struct rb_node pos_node; struct rb_root *pos_root; struct rb_root sort_list; struct request *next_rq; int queued[2]; int allocated[2]; int meta_pending; struct list_head fifo; struct bfq_entity entity; unsigned long max_budget; unsigned long budget_timeout; int dispatched; unsigned short org_ioprio; unsigned short org_ioprio_class; unsigned int flags; struct list_head bfqq_list; unsigned int seek_samples; u64 seek_total; sector_t seek_mean; sector_t last_request_pos; pid_t pid; /* weight-raising fields */ unsigned int raising_cur_max_time; u64 last_rais_start_finish, soft_rt_next_start; unsigned int raising_coeff; }; /** * struct bfq_data - per device data structure. * @queue: request queue for the managed device. * @root_group: root bfq_group for the device. * @rq_pos_tree: rbtree sorted by next_request position, * used when determining if two or more queues * have interleaving requests (see bfq_close_cooperator). * @busy_queues: number of bfq_queues containing requests (including the * queue under service, even if it is idling). * @queued: number of queued requests. * @rq_in_driver: number of requests dispatched and waiting for completion. * @sync_flight: number of sync requests in the driver. * @max_rq_in_driver: max number of reqs in driver in the last @hw_tag_samples * completed requests . * @hw_tag_samples: nr of samples used to calculate hw_tag. * @hw_tag: flag set to one if the driver is showing a queueing behavior. * @budgets_assigned: number of budgets assigned. * @idle_slice_timer: timer set when idling for the next sequential request * from the queue under service. * @unplug_work: delayed work to restart dispatching on the request queue. * @active_queue: bfq_queue under service. * @active_cic: cfq_io_context (cic) associated with the @active_queue. * @last_position: on-disk position of the last served request. * @last_budget_start: beginning of the last budget. * @last_idling_start: beginning of the last idle slice. * @peak_rate: peak transfer rate observed for a budget. * @peak_rate_samples: number of samples used to calculate @peak_rate. * @bfq_max_budget: maximum budget allotted to a bfq_queue before rescheduling. * @cic_index: use small consequent indexes as radix tree keys to reduce depth * @cic_list: list of all the cics active on the bfq_data device. * @group_list: list of all the bfq_groups active on the device. * @active_list: list of all the bfq_queues active on the device. * @idle_list: list of all the bfq_queues idle on the device. * @bfq_quantum: max number of requests dispatched per dispatch round. * @bfq_fifo_expire: timeout for async/sync requests; when it expires * requests are served in fifo order. * @bfq_back_penalty: weight of backward seeks wrt forward ones. * @bfq_back_max: maximum allowed backward seek. * @bfq_slice_idle: maximum idling time. * @bfq_user_max_budget: user-configured max budget value (0 for auto-tuning). * @bfq_max_budget_async_rq: maximum budget (in nr of requests) allotted to * async queues. * @bfq_timeout: timeout for bfq_queues to consume their budget; used to * to prevent seeky queues to impose long latencies to well * behaved ones (this also implies that seeky queues cannot * receive guarantees in the service domain; after a timeout * they are charged for the whole allocated budget, to try * to preserve a behavior reasonably fair among them, but * without service-domain guarantees). * @bfq_raising_coeff: Maximum factor by which the weight of a boosted * queue is multiplied * @bfq_raising_max_time: maximum duration of a weight-raising period (jiffies) * @bfq_raising_rt_max_time: maximum duration for soft real-time processes * @bfq_raising_min_idle_time: minimum idle period after which weight-raising * may be reactivated for a queue (in jiffies) * @bfq_raising_min_inter_arr_async: minimum period between request arrivals * after which weight-raising may be * reactivated for an already busy queue * (in jiffies) * @bfq_raising_max_softrt_rate: max service-rate for a soft real-time queue, * sectors per seconds * @RT_prod: cached value of the product R*T used for computing the maximum * duration of the weight raising automatically * @oom_bfqq: fallback dummy bfqq for extreme OOM conditions * * All the fields are protected by the @queue lock. */ struct bfq_data { struct request_queue *queue; struct bfq_group *root_group; struct rb_root rq_pos_tree; int busy_queues; int queued; int rq_in_driver; int sync_flight; int max_rq_in_driver; int hw_tag_samples; int hw_tag; int budgets_assigned; struct timer_list idle_slice_timer; struct work_struct unplug_work; struct bfq_queue *active_queue; struct cfq_io_context *active_cic; sector_t last_position; ktime_t last_budget_start; ktime_t last_idling_start; int peak_rate_samples; u64 peak_rate; unsigned long bfq_max_budget; unsigned int cic_index; struct list_head cic_list; struct hlist_head group_list; struct list_head active_list; struct list_head idle_list; unsigned int bfq_quantum; unsigned int bfq_fifo_expire[2]; unsigned int bfq_back_penalty; unsigned int bfq_back_max; unsigned int bfq_slice_idle; u64 bfq_class_idle_last_service; unsigned int bfq_user_max_budget; unsigned int bfq_max_budget_async_rq; unsigned int bfq_timeout[2]; bool low_latency; /* parameters of the low_latency heuristics */ unsigned int bfq_raising_coeff; unsigned int bfq_raising_max_time; unsigned int bfq_raising_rt_max_time; unsigned int bfq_raising_min_idle_time; unsigned int bfq_raising_min_inter_arr_async; unsigned int bfq_raising_max_softrt_rate; u64 RT_prod; struct bfq_queue oom_bfqq; }; enum bfqq_state_flags { BFQ_BFQQ_FLAG_busy = 0, /* has requests or is under service */ BFQ_BFQQ_FLAG_wait_request, /* waiting for a request */ BFQ_BFQQ_FLAG_must_alloc, /* must be allowed rq alloc */ BFQ_BFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ BFQ_BFQQ_FLAG_idle_window, /* slice idling enabled */ BFQ_BFQQ_FLAG_prio_changed, /* task priority has changed */ BFQ_BFQQ_FLAG_sync, /* synchronous queue */ BFQ_BFQQ_FLAG_budget_new, /* no completion with this budget */ BFQ_BFQQ_FLAG_coop, /* bfqq is shared */ BFQ_BFQQ_FLAG_split_coop, /* shared bfqq will be splitted */ BFQ_BFQQ_FLAG_some_coop_idle, /* some cooperator is inactive */ }; #define BFQ_BFQQ_FNS(name) \ static inline void bfq_mark_bfqq_##name(struct bfq_queue *bfqq) \ { \ (bfqq)->flags |= (1 << BFQ_BFQQ_FLAG_##name); \ } \ static inline void bfq_clear_bfqq_##name(struct bfq_queue *bfqq) \ { \ (bfqq)->flags &= ~(1 << BFQ_BFQQ_FLAG_##name); \ } \ static inline int bfq_bfqq_##name(const struct bfq_queue *bfqq) \ { \ return ((bfqq)->flags & (1 << BFQ_BFQQ_FLAG_##name)) != 0; \ } BFQ_BFQQ_FNS(busy); BFQ_BFQQ_FNS(wait_request); BFQ_BFQQ_FNS(must_alloc); BFQ_BFQQ_FNS(fifo_expire); BFQ_BFQQ_FNS(idle_window); BFQ_BFQQ_FNS(prio_changed); BFQ_BFQQ_FNS(sync); BFQ_BFQQ_FNS(budget_new); BFQ_BFQQ_FNS(coop); BFQ_BFQQ_FNS(split_coop); BFQ_BFQQ_FNS(some_coop_idle); #undef BFQ_BFQQ_FNS /* Logging facilities. */ #define bfq_log_bfqq(bfqd, bfqq, fmt, args...) \ blk_add_trace_msg((bfqd)->queue, "bfq%d " fmt, (bfqq)->pid, ##args) #define bfq_log(bfqd, fmt, args...) \ blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args) /* Expiration reasons. */ enum bfqq_expiration { BFQ_BFQQ_TOO_IDLE = 0, /* queue has been idling for too long */ BFQ_BFQQ_BUDGET_TIMEOUT, /* budget took too long to be used */ BFQ_BFQQ_BUDGET_EXHAUSTED, /* budget consumed */ BFQ_BFQQ_NO_MORE_REQUESTS, /* the queue has no more requests */ }; #ifdef CONFIG_CGROUP_BFQIO /** * 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). * @group_node: node to be inserted into the bfqio_cgroup->group_data * list of the containing cgroup's bfqio_cgroup. * @bfqd_node: node to be inserted into the @bfqd->group_list list * of the groups active on the same device; used for cleanup. * @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. * * 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 @group_node is protected by the bfqio_cgroup lock, and is accessed * via RCU from its readers. * 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 { struct bfq_entity entity; struct bfq_sched_data sched_data; struct hlist_node group_node; struct hlist_node bfqd_node; void *bfqd; struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR]; struct bfq_queue *async_idle_bfqq; struct bfq_entity *my_entity; }; /** * struct bfqio_cgroup - bfq cgroup data structure. * @css: subsystem state for bfq in the containing cgroup. * @weight: cgroup weight. * @ioprio: cgroup ioprio. * @ioprio_class: cgroup ioprio_class. * @lock: spinlock that protects @ioprio, @ioprio_class and @group_data. * @group_data: list containing the bfq_group belonging to this cgroup. * * @group_data is accessed using RCU, with @lock protecting the updates, * @ioprio and @ioprio_class are protected by @lock. */ struct bfqio_cgroup { struct cgroup_subsys_state css; unsigned short weight, ioprio, ioprio_class; spinlock_t lock; struct hlist_head group_data; }; #else struct bfq_group { struct bfq_sched_data sched_data; struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR]; struct bfq_queue *async_idle_bfqq; }; #endif static inline struct bfq_service_tree * bfq_entity_service_tree(struct bfq_entity *entity) { struct bfq_sched_data *sched_data = entity->sched_data; unsigned int idx = entity->ioprio_class - 1; BUG_ON(idx >= BFQ_IOPRIO_CLASSES); BUG_ON(sched_data == NULL); return sched_data->service_tree + idx; } static inline struct bfq_queue *cic_to_bfqq(struct cfq_io_context *cic, int is_sync) { return cic->cfqq[!!is_sync]; } static inline void cic_set_bfqq(struct cfq_io_context *cic, struct bfq_queue *bfqq, int is_sync) { cic->cfqq[!!is_sync] = bfqq; } static inline void call_for_each_cic(struct io_context *ioc, void (*func)(struct io_context *, struct cfq_io_context *)) { struct cfq_io_context *cic; struct hlist_node *n; rcu_read_lock(); hlist_for_each_entry_rcu(cic, n, &ioc->bfq_cic_list, cic_list) func(ioc, cic); rcu_read_unlock(); } #define CIC_DEAD_KEY 1ul #define CIC_DEAD_INDEX_SHIFT 1 static inline void *bfqd_dead_key(struct bfq_data *bfqd) { return (void *)(bfqd->cic_index << CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY); } /** * bfq_get_bfqd_locked - get a lock to a bfqd using a RCU protected pointer. * @ptr: a pointer to a bfqd. * @flags: storage for the flags to be saved. * * This function allows cic->key and bfqg->bfqd to be protected by the * queue lock of the bfqd they reference; the pointer is dereferenced * under RCU, so the storage for bfqd is assured to be safe as long * as the RCU read side critical section does not end. After the * bfqd->queue->queue_lock is taken the pointer is rechecked, to be * sure that no other writer accessed it. If we raced with a writer, * the function returns NULL, with the queue unlocked, otherwise it * returns the dereferenced pointer, with the queue locked. */ static inline struct bfq_data *bfq_get_bfqd_locked(void **ptr, unsigned long *flags) { struct bfq_data *bfqd; rcu_read_lock(); bfqd = rcu_dereference(*(struct bfq_data **)ptr); if (bfqd != NULL && !((unsigned long) bfqd & CIC_DEAD_KEY)) { spin_lock_irqsave(bfqd->queue->queue_lock, *flags); if (*ptr == bfqd) goto out; spin_unlock_irqrestore(bfqd->queue->queue_lock, *flags); } bfqd = NULL; out: rcu_read_unlock(); return bfqd; } static inline void bfq_put_bfqd_unlock(struct bfq_data *bfqd, unsigned long *flags) { spin_unlock_irqrestore(bfqd->queue->queue_lock, *flags); } static void bfq_changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic); static void bfq_put_queue(struct bfq_queue *bfqq); static void bfq_dispatch_insert(struct request_queue *q, struct request *rq); static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd, struct bfq_group *bfqg, int is_sync, struct io_context *ioc, gfp_t gfp_mask); static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg); static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq); #endif