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-rw-r--r--block/bfq-sched.c1180
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++;
+}