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Diffstat (limited to 'block/bfq-sched.c')
| -rw-r--r-- | block/bfq-sched.c | 1180 |
1 files changed, 1180 insertions, 0 deletions
diff --git a/block/bfq-sched.c b/block/bfq-sched.c new file mode 100644 index 000000000..d0890c6d4 --- /dev/null +++ b/block/bfq-sched.c @@ -0,0 +1,1180 @@ +/* + * BFQ: Hierarchical B-WF2Q+ scheduler. + * + * Based on ideas and code from CFQ: + * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> + * + * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it> + * Paolo Valente <paolo.valente@unimore.it> + * + * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it> + */ + +#ifdef CONFIG_CGROUP_BFQIO +#define for_each_entity(entity) \ + for (; entity != NULL; entity = entity->parent) + +#define for_each_entity_safe(entity, parent) \ + for (; entity && ({ parent = entity->parent; 1; }); entity = parent) + +static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd, + int extract, + struct bfq_data *bfqd); + +static inline void bfq_update_budget(struct bfq_entity *next_in_service) +{ + struct bfq_entity *bfqg_entity; + struct bfq_group *bfqg; + struct bfq_sched_data *group_sd; + + BUG_ON(next_in_service == NULL); + + group_sd = next_in_service->sched_data; + + bfqg = container_of(group_sd, struct bfq_group, sched_data); + /* + * bfq_group's my_entity field is not NULL only if the group + * is not the root group. We must not touch the root entity + * as it must never become an in-service entity. + */ + bfqg_entity = bfqg->my_entity; + if (bfqg_entity != NULL) + bfqg_entity->budget = next_in_service->budget; +} + +static int bfq_update_next_in_service(struct bfq_sched_data *sd) +{ + struct bfq_entity *next_in_service; + + if (sd->in_service_entity != NULL) + /* will update/requeue at the end of service */ + return 0; + + /* + * NOTE: this can be improved in many ways, such as returning + * 1 (and thus propagating upwards the update) only when the + * budget changes, or caching the bfqq that will be scheduled + * next from this subtree. By now we worry more about + * correctness than about performance... + */ + next_in_service = bfq_lookup_next_entity(sd, 0, NULL); + sd->next_in_service = next_in_service; + + if (next_in_service != NULL) + bfq_update_budget(next_in_service); + + return 1; +} + +static inline void bfq_check_next_in_service(struct bfq_sched_data *sd, + struct bfq_entity *entity) +{ + BUG_ON(sd->next_in_service != entity); +} +#else +#define for_each_entity(entity) \ + for (; entity != NULL; entity = NULL) + +#define for_each_entity_safe(entity, parent) \ + for (parent = NULL; entity != NULL; entity = parent) + +static inline int bfq_update_next_in_service(struct bfq_sched_data *sd) +{ + return 0; +} + +static inline void bfq_check_next_in_service(struct bfq_sched_data *sd, + struct bfq_entity *entity) +{ +} + +static inline void bfq_update_budget(struct bfq_entity *next_in_service) +{ +} +#endif + +/* + * Shift for timestamp calculations. This actually limits the maximum + * service allowed in one timestamp delta (small shift values increase it), + * the maximum total weight that can be used for the queues in the system + * (big shift values increase it), and the period of virtual time + * wraparounds. + */ +#define WFQ_SERVICE_SHIFT 22 + +/** + * bfq_gt - compare two timestamps. + * @a: first ts. + * @b: second ts. + * + * Return @a > @b, dealing with wrapping correctly. + */ +static inline int bfq_gt(u64 a, u64 b) +{ + return (s64)(a - b) > 0; +} + +static inline struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity) +{ + struct bfq_queue *bfqq = NULL; + + BUG_ON(entity == NULL); + + if (entity->my_sched_data == NULL) + bfqq = container_of(entity, struct bfq_queue, entity); + + return bfqq; +} + + +/** + * bfq_delta - map service into the virtual time domain. + * @service: amount of service. + * @weight: scale factor (weight of an entity or weight sum). + */ +static inline u64 bfq_delta(unsigned long service, + unsigned long weight) +{ + u64 d = (u64)service << WFQ_SERVICE_SHIFT; + + do_div(d, weight); + return d; +} + +/** + * bfq_calc_finish - assign the finish time to an entity. + * @entity: the entity to act upon. + * @service: the service to be charged to the entity. + */ +static inline void bfq_calc_finish(struct bfq_entity *entity, + unsigned long service) +{ + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + + BUG_ON(entity->weight == 0); + + entity->finish = entity->start + + bfq_delta(service, entity->weight); + + if (bfqq != NULL) { + bfq_log_bfqq(bfqq->bfqd, bfqq, + "calc_finish: serv %lu, w %d", + service, entity->weight); + bfq_log_bfqq(bfqq->bfqd, bfqq, + "calc_finish: start %llu, finish %llu, delta %llu", + entity->start, entity->finish, + bfq_delta(service, entity->weight)); + } +} + +/** + * bfq_entity_of - get an entity from a node. + * @node: the node field of the entity. + * + * Convert a node pointer to the relative entity. This is used only + * to simplify the logic of some functions and not as the generic + * conversion mechanism because, e.g., in the tree walking functions, + * the check for a %NULL value would be redundant. + */ +static inline struct bfq_entity *bfq_entity_of(struct rb_node *node) +{ + struct bfq_entity *entity = NULL; + + if (node != NULL) + entity = rb_entry(node, struct bfq_entity, rb_node); + + return entity; +} + +/** + * bfq_extract - remove an entity from a tree. + * @root: the tree root. + * @entity: the entity to remove. + */ +static inline void bfq_extract(struct rb_root *root, + struct bfq_entity *entity) +{ + BUG_ON(entity->tree != root); + + entity->tree = NULL; + rb_erase(&entity->rb_node, root); +} + +/** + * bfq_idle_extract - extract an entity from the idle tree. + * @st: the service tree of the owning @entity. + * @entity: the entity being removed. + */ +static void bfq_idle_extract(struct bfq_service_tree *st, + struct bfq_entity *entity) +{ + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + struct rb_node *next; + + BUG_ON(entity->tree != &st->idle); + + if (entity == st->first_idle) { + next = rb_next(&entity->rb_node); + st->first_idle = bfq_entity_of(next); + } + + if (entity == st->last_idle) { + next = rb_prev(&entity->rb_node); + st->last_idle = bfq_entity_of(next); + } + + bfq_extract(&st->idle, entity); + + if (bfqq != NULL) + list_del(&bfqq->bfqq_list); +} + +/** + * bfq_insert - generic tree insertion. + * @root: tree root. + * @entity: entity to insert. + * + * This is used for the idle and the active tree, since they are both + * ordered by finish time. + */ +static void bfq_insert(struct rb_root *root, struct bfq_entity *entity) +{ + struct bfq_entity *entry; + struct rb_node **node = &root->rb_node; + struct rb_node *parent = NULL; + + BUG_ON(entity->tree != NULL); + + while (*node != NULL) { + parent = *node; + entry = rb_entry(parent, struct bfq_entity, rb_node); + + if (bfq_gt(entry->finish, entity->finish)) + node = &parent->rb_left; + else + node = &parent->rb_right; + } + + rb_link_node(&entity->rb_node, parent, node); + rb_insert_color(&entity->rb_node, root); + + entity->tree = root; +} + +/** + * bfq_update_min - update the min_start field of a entity. + * @entity: the entity to update. + * @node: one of its children. + * + * This function is called when @entity may store an invalid value for + * min_start due to updates to the active tree. The function assumes + * that the subtree rooted at @node (which may be its left or its right + * child) has a valid min_start value. + */ +static inline void bfq_update_min(struct bfq_entity *entity, + struct rb_node *node) +{ + struct bfq_entity *child; + + if (node != NULL) { + child = rb_entry(node, struct bfq_entity, rb_node); + if (bfq_gt(entity->min_start, child->min_start)) + entity->min_start = child->min_start; + } +} + +/** + * bfq_update_active_node - recalculate min_start. + * @node: the node to update. + * + * @node may have changed position or one of its children may have moved, + * this function updates its min_start value. The left and right subtrees + * are assumed to hold a correct min_start value. + */ +static inline void bfq_update_active_node(struct rb_node *node) +{ + struct bfq_entity *entity = rb_entry(node, struct bfq_entity, rb_node); + + entity->min_start = entity->start; + bfq_update_min(entity, node->rb_right); + bfq_update_min(entity, node->rb_left); +} + +/** + * bfq_update_active_tree - update min_start for the whole active tree. + * @node: the starting node. + * + * @node must be the deepest modified node after an update. This function + * updates its min_start using the values held by its children, assuming + * that they did not change, and then updates all the nodes that may have + * changed in the path to the root. The only nodes that may have changed + * are the ones in the path or their siblings. + */ +static void bfq_update_active_tree(struct rb_node *node) +{ + struct rb_node *parent; + +up: + bfq_update_active_node(node); + + parent = rb_parent(node); + if (parent == NULL) + return; + + if (node == parent->rb_left && parent->rb_right != NULL) + bfq_update_active_node(parent->rb_right); + else if (parent->rb_left != NULL) + bfq_update_active_node(parent->rb_left); + + node = parent; + goto up; +} + +static void bfq_weights_tree_add(struct bfq_data *bfqd, + struct bfq_entity *entity, + struct rb_root *root); + +static void bfq_weights_tree_remove(struct bfq_data *bfqd, + struct bfq_entity *entity, + struct rb_root *root); + + +/** + * bfq_active_insert - insert an entity in the active tree of its + * group/device. + * @st: the service tree of the entity. + * @entity: the entity being inserted. + * + * The active tree is ordered by finish time, but an extra key is kept + * per each node, containing the minimum value for the start times of + * its children (and the node itself), so it's possible to search for + * the eligible node with the lowest finish time in logarithmic time. + */ +static void bfq_active_insert(struct bfq_service_tree *st, + struct bfq_entity *entity) +{ + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + struct rb_node *node = &entity->rb_node; +#ifdef CONFIG_CGROUP_BFQIO + struct bfq_sched_data *sd = NULL; + struct bfq_group *bfqg = NULL; + struct bfq_data *bfqd = NULL; +#endif + + bfq_insert(&st->active, entity); + + if (node->rb_left != NULL) + node = node->rb_left; + else if (node->rb_right != NULL) + node = node->rb_right; + + bfq_update_active_tree(node); + +#ifdef CONFIG_CGROUP_BFQIO + sd = entity->sched_data; + bfqg = container_of(sd, struct bfq_group, sched_data); + BUG_ON(!bfqg); + bfqd = (struct bfq_data *)bfqg->bfqd; +#endif + if (bfqq != NULL) + list_add(&bfqq->bfqq_list, &bfqq->bfqd->active_list); +#ifdef CONFIG_CGROUP_BFQIO + else { /* bfq_group */ + BUG_ON(!bfqd); + bfq_weights_tree_add(bfqd, entity, &bfqd->group_weights_tree); + } + if (bfqg != bfqd->root_group) { + BUG_ON(!bfqg); + BUG_ON(!bfqd); + bfqg->active_entities++; + if (bfqg->active_entities == 2) + bfqd->active_numerous_groups++; + } +#endif +} + +/** + * bfq_ioprio_to_weight - calc a weight from an ioprio. + * @ioprio: the ioprio value to convert. + */ +static inline unsigned short bfq_ioprio_to_weight(int ioprio) +{ + BUG_ON(ioprio < 0 || ioprio >= IOPRIO_BE_NR); + return IOPRIO_BE_NR - ioprio; +} + +/** + * bfq_weight_to_ioprio - calc an ioprio from a weight. + * @weight: the weight value to convert. + * + * To preserve as mush as possible the old only-ioprio user interface, + * 0 is used as an escape ioprio value for weights (numerically) equal or + * larger than IOPRIO_BE_NR + */ +static inline unsigned short bfq_weight_to_ioprio(int weight) +{ + BUG_ON(weight < BFQ_MIN_WEIGHT || weight > BFQ_MAX_WEIGHT); + return IOPRIO_BE_NR - weight < 0 ? 0 : IOPRIO_BE_NR - weight; +} + +static inline void bfq_get_entity(struct bfq_entity *entity) +{ + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + + if (bfqq != NULL) { + atomic_inc(&bfqq->ref); + bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d", + bfqq, atomic_read(&bfqq->ref)); + } +} + +/** + * bfq_find_deepest - find the deepest node that an extraction can modify. + * @node: the node being removed. + * + * Do the first step of an extraction in an rb tree, looking for the + * node that will replace @node, and returning the deepest node that + * the following modifications to the tree can touch. If @node is the + * last node in the tree return %NULL. + */ +static struct rb_node *bfq_find_deepest(struct rb_node *node) +{ + struct rb_node *deepest; + + if (node->rb_right == NULL && node->rb_left == NULL) + deepest = rb_parent(node); + else if (node->rb_right == NULL) + deepest = node->rb_left; + else if (node->rb_left == NULL) + deepest = node->rb_right; + else { + deepest = rb_next(node); + if (deepest->rb_right != NULL) + deepest = deepest->rb_right; + else if (rb_parent(deepest) != node) + deepest = rb_parent(deepest); + } + + return deepest; +} + +/** + * bfq_active_extract - remove an entity from the active tree. + * @st: the service_tree containing the tree. + * @entity: the entity being removed. + */ +static void bfq_active_extract(struct bfq_service_tree *st, + struct bfq_entity *entity) +{ + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + struct rb_node *node; +#ifdef CONFIG_CGROUP_BFQIO + struct bfq_sched_data *sd = NULL; + struct bfq_group *bfqg = NULL; + struct bfq_data *bfqd = NULL; +#endif + + node = bfq_find_deepest(&entity->rb_node); + bfq_extract(&st->active, entity); + + if (node != NULL) + bfq_update_active_tree(node); + +#ifdef CONFIG_CGROUP_BFQIO + sd = entity->sched_data; + bfqg = container_of(sd, struct bfq_group, sched_data); + BUG_ON(!bfqg); + bfqd = (struct bfq_data *)bfqg->bfqd; +#endif + if (bfqq != NULL) + list_del(&bfqq->bfqq_list); +#ifdef CONFIG_CGROUP_BFQIO + else { /* bfq_group */ + BUG_ON(!bfqd); + bfq_weights_tree_remove(bfqd, entity, + &bfqd->group_weights_tree); + } + if (bfqg != bfqd->root_group) { + BUG_ON(!bfqg); + BUG_ON(!bfqd); + BUG_ON(!bfqg->active_entities); + bfqg->active_entities--; + if (bfqg->active_entities == 1) { + BUG_ON(!bfqd->active_numerous_groups); + bfqd->active_numerous_groups--; + } + } +#endif +} + +/** + * bfq_idle_insert - insert an entity into the idle tree. + * @st: the service tree containing the tree. + * @entity: the entity to insert. + */ +static void bfq_idle_insert(struct bfq_service_tree *st, + struct bfq_entity *entity) +{ + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + struct bfq_entity *first_idle = st->first_idle; + struct bfq_entity *last_idle = st->last_idle; + + if (first_idle == NULL || bfq_gt(first_idle->finish, entity->finish)) + st->first_idle = entity; + if (last_idle == NULL || bfq_gt(entity->finish, last_idle->finish)) + st->last_idle = entity; + + bfq_insert(&st->idle, entity); + + if (bfqq != NULL) + list_add(&bfqq->bfqq_list, &bfqq->bfqd->idle_list); +} + +/** + * bfq_forget_entity - remove an entity from the wfq trees. + * @st: the service tree. + * @entity: the entity being removed. + * + * Update the device status and forget everything about @entity, putting + * the device reference to it, if it is a queue. Entities belonging to + * groups are not refcounted. + */ +static void bfq_forget_entity(struct bfq_service_tree *st, + struct bfq_entity *entity) +{ + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + struct bfq_sched_data *sd; + + BUG_ON(!entity->on_st); + + entity->on_st = 0; + st->wsum -= entity->weight; + if (bfqq != NULL) { + sd = entity->sched_data; + bfq_log_bfqq(bfqq->bfqd, bfqq, "forget_entity: %p %d", + bfqq, atomic_read(&bfqq->ref)); + bfq_put_queue(bfqq); + } +} + +/** + * bfq_put_idle_entity - release the idle tree ref of an entity. + * @st: service tree for the entity. + * @entity: the entity being released. + */ +static void bfq_put_idle_entity(struct bfq_service_tree *st, + struct bfq_entity *entity) +{ + bfq_idle_extract(st, entity); + bfq_forget_entity(st, entity); +} + +/** + * bfq_forget_idle - update the idle tree if necessary. + * @st: the service tree to act upon. + * + * To preserve the global O(log N) complexity we only remove one entry here; + * as the idle tree will not grow indefinitely this can be done safely. + */ +static void bfq_forget_idle(struct bfq_service_tree *st) +{ + struct bfq_entity *first_idle = st->first_idle; + struct bfq_entity *last_idle = st->last_idle; + + if (RB_EMPTY_ROOT(&st->active) && last_idle != NULL && + !bfq_gt(last_idle->finish, st->vtime)) { + /* + * Forget the whole idle tree, increasing the vtime past + * the last finish time of idle entities. + */ + st->vtime = last_idle->finish; + } + + if (first_idle != NULL && !bfq_gt(first_idle->finish, st->vtime)) + bfq_put_idle_entity(st, first_idle); +} + +static struct bfq_service_tree * +__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st, + struct bfq_entity *entity) +{ + struct bfq_service_tree *new_st = old_st; + + if (entity->ioprio_changed) { + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + unsigned short prev_weight, new_weight; + struct bfq_data *bfqd = NULL; + struct rb_root *root; +#ifdef CONFIG_CGROUP_BFQIO + struct bfq_sched_data *sd; + struct bfq_group *bfqg; +#endif + + if (bfqq != NULL) + bfqd = bfqq->bfqd; +#ifdef CONFIG_CGROUP_BFQIO + else { + sd = entity->my_sched_data; + bfqg = container_of(sd, struct bfq_group, sched_data); + BUG_ON(!bfqg); + bfqd = (struct bfq_data *)bfqg->bfqd; + BUG_ON(!bfqd); + } +#endif + + BUG_ON(old_st->wsum < entity->weight); + old_st->wsum -= entity->weight; + + if (entity->new_weight != entity->orig_weight) { + if (entity->new_weight < BFQ_MIN_WEIGHT || + entity->new_weight > BFQ_MAX_WEIGHT) { + printk(KERN_CRIT "update_weight_prio: " + "new_weight %d\n", + entity->new_weight); + BUG(); + } + entity->orig_weight = entity->new_weight; + entity->ioprio = + bfq_weight_to_ioprio(entity->orig_weight); + } + + entity->ioprio_class = entity->new_ioprio_class; + entity->ioprio_changed = 0; + + /* + * NOTE: here we may be changing the weight too early, + * this will cause unfairness. The correct approach + * would have required additional complexity to defer + * weight changes to the proper time instants (i.e., + * when entity->finish <= old_st->vtime). + */ + new_st = bfq_entity_service_tree(entity); + + prev_weight = entity->weight; + new_weight = entity->orig_weight * + (bfqq != NULL ? bfqq->wr_coeff : 1); + /* + * If the weight of the entity changes, remove the entity + * from its old weight counter (if there is a counter + * associated with the entity), and add it to the counter + * associated with its new weight. + */ + if (prev_weight != new_weight) { + root = bfqq ? &bfqd->queue_weights_tree : + &bfqd->group_weights_tree; + bfq_weights_tree_remove(bfqd, entity, root); + } + entity->weight = new_weight; + /* + * Add the entity to its weights tree only if it is + * not associated with a weight-raised queue. + */ + if (prev_weight != new_weight && + (bfqq ? bfqq->wr_coeff == 1 : 1)) + /* If we get here, root has been initialized. */ + bfq_weights_tree_add(bfqd, entity, root); + + new_st->wsum += entity->weight; + + if (new_st != old_st) + entity->start = new_st->vtime; + } + + return new_st; +} + +/** + * bfq_bfqq_served - update the scheduler status after selection for + * service. + * @bfqq: the queue being served. + * @served: bytes to transfer. + * + * NOTE: this can be optimized, as the timestamps of upper level entities + * are synchronized every time a new bfqq is selected for service. By now, + * we keep it to better check consistency. + */ +static void bfq_bfqq_served(struct bfq_queue *bfqq, unsigned long served) +{ + struct bfq_entity *entity = &bfqq->entity; + struct bfq_service_tree *st; + + for_each_entity(entity) { + st = bfq_entity_service_tree(entity); + + entity->service += served; + BUG_ON(entity->service > entity->budget); + BUG_ON(st->wsum == 0); + + st->vtime += bfq_delta(served, st->wsum); + bfq_forget_idle(st); + } + bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %lu secs", served); +} + +/** + * bfq_bfqq_charge_full_budget - set the service to the entity budget. + * @bfqq: the queue that needs a service update. + * + * When it's not possible to be fair in the service domain, because + * a queue is not consuming its budget fast enough (the meaning of + * fast depends on the timeout parameter), we charge it a full + * budget. In this way we should obtain a sort of time-domain + * fairness among all the seeky/slow queues. + */ +static inline void bfq_bfqq_charge_full_budget(struct bfq_queue *bfqq) +{ + struct bfq_entity *entity = &bfqq->entity; + + bfq_log_bfqq(bfqq->bfqd, bfqq, "charge_full_budget"); + + bfq_bfqq_served(bfqq, entity->budget - entity->service); +} + +/** + * __bfq_activate_entity - activate an entity. + * @entity: the entity being activated. + * + * Called whenever an entity is activated, i.e., it is not active and one + * of its children receives a new request, or has to be reactivated due to + * budget exhaustion. It uses the current budget of the entity (and the + * service received if @entity is active) of the queue to calculate its + * timestamps. + */ +static void __bfq_activate_entity(struct bfq_entity *entity) +{ + struct bfq_sched_data *sd = entity->sched_data; + struct bfq_service_tree *st = bfq_entity_service_tree(entity); + + if (entity == sd->in_service_entity) { + BUG_ON(entity->tree != NULL); + /* + * If we are requeueing the current entity we have + * to take care of not charging to it service it has + * not received. + */ + bfq_calc_finish(entity, entity->service); + entity->start = entity->finish; + sd->in_service_entity = NULL; + } else if (entity->tree == &st->active) { + /* + * Requeueing an entity due to a change of some + * next_in_service entity below it. We reuse the + * old start time. + */ + bfq_active_extract(st, entity); + } else if (entity->tree == &st->idle) { + /* + * Must be on the idle tree, bfq_idle_extract() will + * check for that. + */ + bfq_idle_extract(st, entity); + entity->start = bfq_gt(st->vtime, entity->finish) ? + st->vtime : entity->finish; + } else { + /* + * The finish time of the entity may be invalid, and + * it is in the past for sure, otherwise the queue + * would have been on the idle tree. + */ + entity->start = st->vtime; + st->wsum += entity->weight; + bfq_get_entity(entity); + + BUG_ON(entity->on_st); + entity->on_st = 1; + } + + st = __bfq_entity_update_weight_prio(st, entity); + bfq_calc_finish(entity, entity->budget); + bfq_active_insert(st, entity); +} + +/** + * bfq_activate_entity - activate an entity and its ancestors if necessary. + * @entity: the entity to activate. + * + * Activate @entity and all the entities on the path from it to the root. + */ +static void bfq_activate_entity(struct bfq_entity *entity) +{ + struct bfq_sched_data *sd; + + for_each_entity(entity) { + __bfq_activate_entity(entity); + + sd = entity->sched_data; + if (!bfq_update_next_in_service(sd)) + /* + * No need to propagate the activation to the + * upper entities, as they will be updated when + * the in-service entity is rescheduled. + */ + break; + } +} + +/** + * __bfq_deactivate_entity - deactivate an entity from its service tree. + * @entity: the entity to deactivate. + * @requeue: if false, the entity will not be put into the idle tree. + * + * Deactivate an entity, independently from its previous state. If the + * entity was not on a service tree just return, otherwise if it is on + * any scheduler tree, extract it from that tree, and if necessary + * and if the caller did not specify @requeue, put it on the idle tree. + * + * Return %1 if the caller should update the entity hierarchy, i.e., + * if the entity was in service or if it was the next_in_service for + * its sched_data; return %0 otherwise. + */ +static int __bfq_deactivate_entity(struct bfq_entity *entity, int requeue) +{ + struct bfq_sched_data *sd = entity->sched_data; + struct bfq_service_tree *st = bfq_entity_service_tree(entity); + int was_in_service = entity == sd->in_service_entity; + int ret = 0; + + if (!entity->on_st) + return 0; + + BUG_ON(was_in_service && entity->tree != NULL); + + if (was_in_service) { + bfq_calc_finish(entity, entity->service); + sd->in_service_entity = NULL; + } else if (entity->tree == &st->active) + bfq_active_extract(st, entity); + else if (entity->tree == &st->idle) + bfq_idle_extract(st, entity); + else if (entity->tree != NULL) + BUG(); + + if (was_in_service || sd->next_in_service == entity) + ret = bfq_update_next_in_service(sd); + + if (!requeue || !bfq_gt(entity->finish, st->vtime)) + bfq_forget_entity(st, entity); + else + bfq_idle_insert(st, entity); + + BUG_ON(sd->in_service_entity == entity); + BUG_ON(sd->next_in_service == entity); + + return ret; +} + +/** + * bfq_deactivate_entity - deactivate an entity. + * @entity: the entity to deactivate. + * @requeue: true if the entity can be put on the idle tree + */ +static void bfq_deactivate_entity(struct bfq_entity *entity, int requeue) +{ + struct bfq_sched_data *sd; + struct bfq_entity *parent; + + for_each_entity_safe(entity, parent) { + sd = entity->sched_data; + + if (!__bfq_deactivate_entity(entity, requeue)) + /* + * The parent entity is still backlogged, and + * we don't need to update it as it is still + * in service. + */ + break; + + if (sd->next_in_service != NULL) + /* + * The parent entity is still backlogged and + * the budgets on the path towards the root + * need to be updated. + */ + goto update; + + /* + * If we reach there the parent is no more backlogged and + * we want to propagate the dequeue upwards. + */ + requeue = 1; + } + + return; + +update: + entity = parent; + for_each_entity(entity) { + __bfq_activate_entity(entity); + + sd = entity->sched_data; + if (!bfq_update_next_in_service(sd)) + break; + } +} + +/** + * bfq_update_vtime - update vtime if necessary. + * @st: the service tree to act upon. + * + * If necessary update the service tree vtime to have at least one + * eligible entity, skipping to its start time. Assumes that the + * active tree of the device is not empty. + * + * NOTE: this hierarchical implementation updates vtimes quite often, + * we may end up with reactivated processes getting timestamps after a + * vtime skip done because we needed a ->first_active entity on some + * intermediate node. + */ +static void bfq_update_vtime(struct bfq_service_tree *st) +{ + struct bfq_entity *entry; + struct rb_node *node = st->active.rb_node; + + entry = rb_entry(node, struct bfq_entity, rb_node); + if (bfq_gt(entry->min_start, st->vtime)) { + st->vtime = entry->min_start; + bfq_forget_idle(st); + } +} + +/** + * bfq_first_active_entity - find the eligible entity with + * the smallest finish time + * @st: the service tree to select from. + * + * This function searches the first schedulable entity, starting from the + * root of the tree and going on the left every time on this side there is + * a subtree with at least one eligible (start >= vtime) entity. The path on + * the right is followed only if a) the left subtree contains no eligible + * entities and b) no eligible entity has been found yet. + */ +static struct bfq_entity *bfq_first_active_entity(struct bfq_service_tree *st) +{ + struct bfq_entity *entry, *first = NULL; + struct rb_node *node = st->active.rb_node; + + while (node != NULL) { + entry = rb_entry(node, struct bfq_entity, rb_node); +left: + if (!bfq_gt(entry->start, st->vtime)) + first = entry; + + BUG_ON(bfq_gt(entry->min_start, st->vtime)); + + if (node->rb_left != NULL) { + entry = rb_entry(node->rb_left, + struct bfq_entity, rb_node); + if (!bfq_gt(entry->min_start, st->vtime)) { + node = node->rb_left; + goto left; + } + } + if (first != NULL) + break; + node = node->rb_right; + } + + BUG_ON(first == NULL && !RB_EMPTY_ROOT(&st->active)); + return first; +} + +/** + * __bfq_lookup_next_entity - return the first eligible entity in @st. + * @st: the service tree. + * + * Update the virtual time in @st and return the first eligible entity + * it contains. + */ +static struct bfq_entity *__bfq_lookup_next_entity(struct bfq_service_tree *st, + bool force) +{ + struct bfq_entity *entity, *new_next_in_service = NULL; + + if (RB_EMPTY_ROOT(&st->active)) + return NULL; + + bfq_update_vtime(st); + entity = bfq_first_active_entity(st); + BUG_ON(bfq_gt(entity->start, st->vtime)); + + /* + * If the chosen entity does not match with the sched_data's + * next_in_service and we are forcedly serving the IDLE priority + * class tree, bubble up budget update. + */ + if (unlikely(force && entity != entity->sched_data->next_in_service)) { + new_next_in_service = entity; + for_each_entity(new_next_in_service) + bfq_update_budget(new_next_in_service); + } + + return entity; +} + +/** + * bfq_lookup_next_entity - return the first eligible entity in @sd. + * @sd: the sched_data. + * @extract: if true the returned entity will be also extracted from @sd. + * + * NOTE: since we cache the next_in_service entity at each level of the + * hierarchy, the complexity of the lookup can be decreased with + * absolutely no effort just returning the cached next_in_service value; + * we prefer to do full lookups to test the consistency of * the data + * structures. + */ +static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd, + int extract, + struct bfq_data *bfqd) +{ + struct bfq_service_tree *st = sd->service_tree; + struct bfq_entity *entity; + int i = 0; + + BUG_ON(sd->in_service_entity != NULL); + + if (bfqd != NULL && + jiffies - bfqd->bfq_class_idle_last_service > BFQ_CL_IDLE_TIMEOUT) { + entity = __bfq_lookup_next_entity(st + BFQ_IOPRIO_CLASSES - 1, + true); + if (entity != NULL) { + i = BFQ_IOPRIO_CLASSES - 1; + bfqd->bfq_class_idle_last_service = jiffies; + sd->next_in_service = entity; + } + } + for (; i < BFQ_IOPRIO_CLASSES; i++) { + entity = __bfq_lookup_next_entity(st + i, false); + if (entity != NULL) { + if (extract) { + bfq_check_next_in_service(sd, entity); + bfq_active_extract(st + i, entity); + sd->in_service_entity = entity; + sd->next_in_service = NULL; + } + break; + } + } + + return entity; +} + +/* + * Get next queue for service. + */ +static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd) +{ + struct bfq_entity *entity = NULL; + struct bfq_sched_data *sd; + struct bfq_queue *bfqq; + + BUG_ON(bfqd->in_service_queue != NULL); + + if (bfqd->busy_queues == 0) + return NULL; + + sd = &bfqd->root_group->sched_data; + for (; sd != NULL; sd = entity->my_sched_data) { + entity = bfq_lookup_next_entity(sd, 1, bfqd); + BUG_ON(entity == NULL); + entity->service = 0; + } + + bfqq = bfq_entity_to_bfqq(entity); + BUG_ON(bfqq == NULL); + + return bfqq; +} + +static void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd) +{ + if (bfqd->in_service_bic != NULL) { + put_io_context(bfqd->in_service_bic->icq.ioc); + bfqd->in_service_bic = NULL; + } + + bfqd->in_service_queue = NULL; + del_timer(&bfqd->idle_slice_timer); +} + +static void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, + int requeue) +{ + struct bfq_entity *entity = &bfqq->entity; + + if (bfqq == bfqd->in_service_queue) + __bfq_bfqd_reset_in_service(bfqd); + + bfq_deactivate_entity(entity, requeue); +} + +static void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) +{ + struct bfq_entity *entity = &bfqq->entity; + + bfq_activate_entity(entity); +} + +/* + * Called when the bfqq no longer has requests pending, remove it from + * the service tree. + */ +static void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq, + int requeue) +{ + BUG_ON(!bfq_bfqq_busy(bfqq)); + BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list)); + + bfq_log_bfqq(bfqd, bfqq, "del from busy"); + + bfq_clear_bfqq_busy(bfqq); + + BUG_ON(bfqd->busy_queues == 0); + bfqd->busy_queues--; + + if (!bfqq->dispatched) { + bfq_weights_tree_remove(bfqd, &bfqq->entity, + &bfqd->queue_weights_tree); + if (!blk_queue_nonrot(bfqd->queue)) { + BUG_ON(!bfqd->busy_in_flight_queues); + bfqd->busy_in_flight_queues--; + if (bfq_bfqq_constantly_seeky(bfqq)) { + BUG_ON(!bfqd-> + const_seeky_busy_in_flight_queues); + bfqd->const_seeky_busy_in_flight_queues--; + } + } + } + if (bfqq->wr_coeff > 1) + bfqd->wr_busy_queues--; + + bfq_deactivate_bfqq(bfqd, bfqq, requeue); +} + +/* + * Called when an inactive queue receives a new request. + */ +static void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq) +{ + BUG_ON(bfq_bfqq_busy(bfqq)); + BUG_ON(bfqq == bfqd->in_service_queue); + + bfq_log_bfqq(bfqd, bfqq, "add to busy"); + + bfq_activate_bfqq(bfqd, bfqq); + + bfq_mark_bfqq_busy(bfqq); + bfqd->busy_queues++; + + if (!bfqq->dispatched) { + if (bfqq->wr_coeff == 1) + bfq_weights_tree_add(bfqd, &bfqq->entity, + &bfqd->queue_weights_tree); + if (!blk_queue_nonrot(bfqd->queue)) { + bfqd->busy_in_flight_queues++; + if (bfq_bfqq_constantly_seeky(bfqq)) + bfqd->const_seeky_busy_in_flight_queues++; + } + } + if (bfqq->wr_coeff > 1) + bfqd->wr_busy_queues++; +} |