// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Hierarchical Budget Worst-case Fair Weighted Fair Queueing
* (B-WF2Q+): hierarchical scheduling algorithm by which the BFQ I/O
* scheduler schedules generic entities. The latter can represent
* either single bfq queues (associated with processes) or groups of
* bfq queues (associated with cgroups).
*/
#include "bfq-iosched.h"
/**
* bfq_gt - compare two timestamps.
* @a: first ts.
* @b: second ts.
*
* Return @a > @b, dealing with wrapping correctly.
*/
static int bfq_gt(u64 a, u64 b)
{
return (s64)(a - b) > 0;
}
static struct bfq_entity *bfq_root_active_entity(struct rb_root *tree)
{
struct rb_node *node = tree->rb_node;
return rb_entry(node, struct bfq_entity, rb_node);
}
static unsigned int bfq_class_idx(struct bfq_entity *entity)
{
struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
return bfqq ? bfqq->ioprio_class - 1 :
BFQ_DEFAULT_GRP_CLASS - 1;
}
unsigned int bfq_tot_busy_queues(struct bfq_data *bfqd)
{
return bfqd->busy_queues[0] + bfqd->busy_queues[1] +
bfqd->busy_queues[2];
}
static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
bool expiration);
static bool bfq_update_parent_budget(struct bfq_entity *next_in_service);
/**
* bfq_update_next_in_service - update sd->next_in_service
* @sd: sched_data for which to perform the update.
* @new_entity: if not NULL, pointer to the entity whose activation,
* requeueing or repositioning triggered the invocation of
* this function.
* @expiration: id true, this function is being invoked after the
* expiration of the in-service entity
*
* This function is called to update sd->next_in_service, which, in
* its turn, may change as a consequence of the insertion or
* extraction of an entity into/from one of the active trees of
* sd. These insertions/extractions occur as a consequence of
* activations/deactivations of entities, with some activations being
* 'true' activations, and other activations being requeueings (i.e.,
* implementing the second, requeueing phase of the mechanism used to
* reposition an entity in its active tree; see comments on
* __bfq_activate_entity and __bfq_requeue_entity for details). In
* both the last two activation sub-cases, new_entity points to the
* just activated or requeued entity.
*
* Returns true if sd->next_in_service changes in such a way that
* entity->parent may become the next_in_service for its parent
* entity.
*/
static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
struct bfq_entity *new_entity,
bool expiration)
{
struct bfq_entity *next_in_service = sd->next_in_service;
bool parent_sched_may_change = false;
bool change_without_lookup = false;
/*
* If this update is triggered by the activation, requeueing
* or repositioning of an entity that does not coincide with
* sd->next_in_service, then a full lookup in the active tree
* can be avoided. In fact, it is enough to check whether the
* just-modified entity has the same priority as
* sd->next_in_service, is eligible and has a lower virtual
* finish time than sd->next_in_service. If this compound
* condition holds, then the new entity becomes the new
* next_in_service. Otherwise no change is needed.
*/
if (new_entity && new_entity != sd->next_in_service) {
/*
* Flag used to decide whether to replace
* sd->next_in_service with new_entity. Tentatively
* set to true, and left as true if
* sd->next_in_service is NULL.
*/
change_without_lookup = true;
/*
* If there is already a next_in_service candidate
* entity, then compare timestamps to decide whether
* to replace sd->service_tree with new_entity.
*/
if (next_in_service) {
unsigned int new_entity_class_idx =
bfq_class_idx(new_entity);
struct bfq_service_tree *st =
sd->service_tree + new_entity_class_idx;
change_without_lookup =
(new_entity_class_idx ==
bfq_class_idx(next_in_service)
&&
!bfq_gt(new_entity->start, st->vtime)
&&
bfq_gt(next_in_service->finish,
new_entity->finish));
}
if (change_without_lookup)
next_in_service = new_entity;
}
if (!change_without_lookup) /* lookup needed */
next_in_service = bfq_lookup_next_entity(sd, expiration);
if (next_in_service) {
bool new_budget_triggers_change =
bfq_update_parent_budget(next_in_service);
parent_sched_may_change = !sd->next_in_service ||
new_budget_triggers_change;
}
sd->next_in_service = next_in_service;
return parent_sched_may_change;
}
#ifdef CONFIG_BFQ_GROUP_IOSCHED
/*
* Returns true if this budget changes may let next_in_service->parent
* become the next_in_service entity for its parent entity.
*/
static bool bfq_update_parent_budget(struct bfq_entity *next_in_service)
{
struct bfq_entity *bfqg_entity;
struct bfq_group *bfqg;
struct bfq_sched_data *group_sd;
bool ret = false;
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) {
if (bfqg_entity->budget > next_in_service->budget)
ret = true;
bfqg_entity->budget = next_in_service->budget;
}
return ret;
}
/*
* This function tells whether entity stops being a candidate for next
* service, according to the restrictive definition of the field
* next_in_service. In particular, this function is invoked for an
* entity that is about to be set in service.
*
* If entity is a queue, then the entity is no longer a candidate for
* next service according to the that definition, because entity is
* about to become the in-service queue. This function then returns
* true if entity is a queue.
*
* In contrast, entity could still be a candidate for next service if
* it is not a queue, and has more than one active child. In fact,
* even if one of its children is about to be set in service, other
* active children may still be the next to serve, for the parent
* entity, even according to the above definition. As a consequence, a
* non-queue entity is not a candidate for next-service only if it has
* only one active child. And only if this condition holds, then this
* function returns true for a non-queue entity.
*/
static bool bfq_no_longer_next_in_service(struct bfq_entity *entity)
{
struct bfq_group *bfqg;
if (bfq_entity_to_bfqq(entity))
return true;
bfqg = container_of(entity, struct bfq_group, entity);
/*
* The field active_entities does not always contain the
* actual number of active children entities: it happens to
* not account for the in-service entity in case the latter is
* removed from its active tree (which may get done after
* invoking the function bfq_no_longer_next_in_service in
* bfq_get_next_queue). Fortunately, here, i.e., while
* bfq_no_longer_next_in_service is not yet completed in
* bfq_get_next_queue, bfq_active_extract has not yet been
* invoked, and thus active_entities still coincides with the
* actual number of active entities.
*/
if (bfqg->active_entities == 1)
return true;
return false;
}
static void bfq_inc_active_entities(struct bfq_entity *entity)
{
struct bfq_sched_data *sd = entity->sched_data;
struct bfq_group *bfqg = container_of(sd, struct bfq_group, sched_data);
if (bfqg != bfqg->bfqd->root_group)
bfqg->active_entities++;
}
static void bfq_dec_active_entities(struct bfq_entity *entity)
{
struct bfq_sched_data *sd = entity->sched_data;
struct bfq_group *bfqg = container_of(sd, struct bfq_group, sched_data);
if (bfqg != bfqg->bfqd->root_group)
bfqg->active_entities--;
}
#else /* CONFIG_BFQ_GROUP_IOSCHED */
static bool bfq_update_parent_budget(struct bfq_entity *next_in_service)
{
return false;
}
static bool bfq_no_longer_next_in_service(struct bfq_entity *entity)
{
return true;
}
static void bfq_inc_active_entities(struct bfq_entity *entity)
{
}
static void bfq_dec_active_entities(struct bfq_entity *entity)
{
}
#endif /* CONFIG_BFQ_GROUP_IOSCHED */
/*
* 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
struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity)
{
struct bfq_queue *bfqq = NULL;
if (!entity->my_sched_data)
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 u64 bfq_delta(unsigned long service, unsigned long weight)
{
return div64_ul((u64)service << WFQ_SERVICE_SHIFT, weight);
}
/**
* 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 void bfq_calc_finish(struct bfq_entity *entity, unsigned long service)
{
struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
entity->finish = entity->start +
bfq_delta(service, entity->weight);
if (bfqq) {
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.
*/
struct bfq_entity *bfq_entity_of(struct rb_node *node)
{
struct bfq_entity *entity = NULL;
if (node)
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 void bfq_extract(struct rb_root *root, struct bfq_entity *entity)
{
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;
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)
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;
while (*node) {
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 void bfq_update_min(struct bfq_entity *entity, struct rb_node *node)
{
struct bfq_entity *child;
if (node) {
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 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)
return;
if (node == parent->rb_left && parent->rb_right)
bfq_update_active_node(parent->rb_right);
else if (parent->rb_left)
bfq_update_active_node(parent->rb_left);
node = parent;
goto up;
}
/**
* 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;
bfq_insert(&st->active, entity);
if (node->rb_left)
node = node->rb_left;
else if (node->rb_right)
node = node->rb_right;
bfq_update_active_tree(node);
if (bfqq)
list_add(&bfqq->bfqq_list, &bfqq->bfqd->active_list[bfqq->actuator_idx]);
bfq_inc_active_entities(entity);
}
/**
* bfq_ioprio_to_weight - calc a weight from an ioprio.
* @ioprio: the ioprio value to convert.
*/
unsigned short bfq_ioprio_to_weight(int ioprio)
{
return (IOPRIO_NR_LEVELS - ioprio) * BFQ_WEIGHT_CONVERSION_COEFF;
}
/**
* bfq_weight_to_ioprio - calc an ioprio from a weight.
* @weight: the weight value to convert.
*
* To preserve as much as possible the old only-ioprio user interface,
* 0 is used as an escape ioprio value for weights (numerically) equal or
* larger than IOPRIO_NR_LEVELS * BFQ_WEIGHT_CONVERSION_COEFF.
*/
static unsigned short bfq_weight_to_ioprio(int weight)
{
return max_t(int, 0,
IOPRIO_NR_LEVELS - weight / BFQ_WEIGHT_CONVERSION_COEFF);
}
static void bfq_get_entity(struct bfq_entity *entity)
{
struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
if (bfqq) {
bfqq->ref++;
bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d",
bfqq, 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 && !node->rb_left)
deepest = rb_parent(node);
else if (!node->rb_right)
deepest = node->rb_left;
else if (!node->rb_left)
deepest = node->rb_right;
else {
deepest = rb_next(node);
if (deepest->rb_right)
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;
node = bfq_find_deepest(&entity->rb_node);
bfq_extract(&st->active, entity);
if (node)
bfq_update_active_tree(node);
if (bfqq)
list_del(&bfqq->bfqq_list);
bfq_dec_active_entities(entity);
}
/**
* 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 || bfq_gt(first_idle->finish, entity->finish))
st->first_idle = entity;
if (!last_idle || bfq_gt(entity->finish, last_idle->finish))
st->last_idle = entity;
bfq_insert(&st->idle, entity);
if (bfqq)
list_add(&bfqq->bfqq_list, &bfqq->bfqd->idle_list);
}
/**
* bfq_forget_entity - do not consider entity any longer for scheduling
* @st: the service tree.
* @entity: the entity being removed.
* @is_in_service: true if entity is currently the in-service entity.
*
* Forget everything about @entity. In addition, if entity represents
* a queue, and the latter is not in service, then release the service
* reference to the queue (the one taken through bfq_get_entity). In
* fact, in this case, there is really no more service reference to
* the queue, as the latter is also outside any service tree. If,
* instead, the queue is in service, then __bfq_bfqd_reset_in_service
* will take care of putting the reference when the queue finally
* stops being served.
*/
static void bfq_forget_entity(struct bfq_service_tree *st,
struct bfq_entity *entity,
bool is_in_service)
{
struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
entity->on_st_or_in_serv = false;
st->wsum -= entity->weight;
if (bfqq && !is_in_service)
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.
*/
void bfq_put_idle_entity(struct bfq_service_tree *st, struct bfq_entity *entity)
{
bfq_idle_extract(st, entity);
bfq_forget_entity(st, entity,
entity == entity->sched_data->in_service_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 &&
!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 && !bfq_gt(first_idle->finish, st->vtime))
bfq_put_idle_entity(st, first_idle);
}
struct bfq_service_tree *bfq_entity_service_tree(struct bfq_entity *entity)
{
struct bfq_sched_data *sched_data = entity->sched_data;
unsigned int idx = bfq_class_idx(entity);
return sched_data->service_tree + idx;
}
/*
* Update weight and priority of entity. If update_class_too is true,
* then update the ioprio_class of entity too.
*
* The reason why the update of ioprio_class is controlled through the
* last parameter is as follows. Changing the ioprio class of an
* entity implies changing the destination service trees for that
* entity. If such a change occurred when the entity is already on one
* of the service trees for its previous class, then the state of the
* entity would become more complex: none of the new possible service
* trees for the entity, according to bfq_entity_service_tree(), would
* match any of the possible service trees on which the entity
* is. Complex operations involving these trees, such as entity
* activations and deactivations, should take into account this
* additional complexity. To avoid this issue, this function is
* invoked with update_class_too unset in the points in the code where
* entity may happen to be on some tree.
*/
struct bfq_service_tree *
__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
struct bfq_entity *entity,
bool update_class_too)
{
struct bfq_service_tree *new_st = old_st;
if (entity->prio_changed) {
struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
unsigned int prev_weight, new_weight;
/* Matches the smp_wmb() in bfq_group_set_weight. */
smp_rmb();
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) {
pr_crit("update_weight_prio: new_weight %d\n",
entity->new_weight);
if (entity->new_weight < BFQ_MIN_WEIGHT)
entity->new_weight = BFQ_MIN_WEIGHT;
else
entity->new_weight = BFQ_MAX_WEIGHT;
}
entity->orig_weight = entity->new_weight;
if (bfqq)
bfqq->ioprio =
bfq_weight_to_ioprio(entity->orig_weight);
}
if (bfqq && update_class_too)
bfqq->ioprio_class = bfqq->new_ioprio_class;
/*
* Reset prio_changed only if the ioprio_class change
* is not pending any longer.
*/
if (!bfqq || bfqq->ioprio_class == bfqq->new_ioprio_class)
entity->prio_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 ? bfqq->wr_coeff : 1);
/*
* If the weight of the entity changes, and the entity is a
* queue, remove the entity from its old weight counter (if
* there is a counter associated with the entity).
*/
if (prev_weight != new_weight && bfqq)
bfq_weights_tree_remove(bfqq);
entity->weight = new_weight;
/*
* Add the entity, if it is not a weight-raised queue,
* to the counter associated with its new weight.
*/
if (prev_weight != new_weight && bfqq && bfqq->wr_coeff == 1)
bfq_weights_tree_add(bfqq);
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.
*/
void bfq_bfqq_served(struct bfq_queue *bfqq, int served)
{
struct bfq_entity *entity = &bfqq->entity;
struct bfq_service_tree *st;
if (!bfqq->service_from_backlogged)
bfqq->first_IO_time = jiffies;
if (bfqq->wr_coeff > 1)
bfqq->service_from_wr += served;
bfqq->service_from_backlogged += served;
for_each_entity(entity) {
st = bfq_entity_service_tree(entity);
entity->service += served;
st->vtime += bfq_delta(served, st->wsum);
bfq_forget_idle(st);
}
bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %d secs", served);
}
/**
* bfq_bfqq_charge_time - charge an amount of service equivalent to the length
* of the time interval during which bfqq has been in
* service.
* @bfqd: the device
* @bfqq: the queue that needs a service update.
* @time_ms: the amount of time during which the queue has received service
*
* If a queue does not consume its budget fast enough, then providing
* the queue with service fairness may impair throughput, more or less
* severely. For this reason, queues that consume their budget slowly
* are provided with time fairness instead of service fairness. This
* goal is achieved through the BFQ scheduling engine, even if such an
* engine works in the service, and not in the time domain. The trick
* is charging these queues with an inflated amount of service, equal
* to the amount of service that they would have received during their
* service slot if they had been fast, i.e., if their requests had
* been dispatched at a rate equal to the estimated peak rate.
*
* It is worth noting that time fairness can cause important
* distortions in terms of bandwidth distribution, on devices with
* internal queueing. The reason is that I/O requests dispatched
* during the service slot of a queue may be served after that service
* slot is finished, and may have a total processing time loosely
* correlated with the duration of the service slot. This is
* especially true for short service slots.
*/
void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq,
unsigned long time_ms)
{
struct bfq_entity *entity = &bfqq->entity;
unsigned long timeout_ms = jiffies_to_msecs(bfq_timeout);
unsigned long bounded_time_ms = min(time_ms, timeout_ms);
int serv_to_charge_for_time =
(bfqd->bfq_max_budget * bounded_time_ms) / timeout_ms;
int tot_serv_to_charge = max(serv_to_charge_for_time, entity->service);
/* Increase budget to avoid inconsistencies */
if (tot_serv_to_charge > entity->budget)
entity->budget = tot_serv_to_charge;
bfq_bfqq_served(bfqq,
max_t(int, 0, tot_serv_to_charge - entity->service));
}
static void bfq_update_fin_time_enqueue(struct bfq_entity *entity,
struct bfq_service_tree *st,
bool backshifted)
{
struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
/*
* When this function is invoked, entity is not in any service
* tree, then it is safe to invoke next function with the last
* parameter set (see the comments on the function).
*/
st = __bfq_entity_update_weight_prio(st, entity, true);
bfq_calc_finish(entity, entity->budget);
/*
* If some queues enjoy backshifting for a while, then their
* (virtual) finish timestamps may happen to become lower and
* lower than the system virtual time. In particular, if
* these queues often happen to be idle for short time
* periods, and during such time periods other queues with
* higher timestamps happen to be busy, then the backshifted
* timestamps of the former queues can become much lower than
* the system virtual time. In fact, to serve the queues with
* higher timestamps while the ones with lower timestamps are
* idle, the system virtual time may be pushed-up to much
* higher values than the finish timestamps of the idle
* queues. As a consequence, the finish timestamps of all new
* or newly activated queues may end up being much larger than
* those of lucky queues with backshifted timestamps. The
* latter queues may then monopolize the device for a lot of
* time. This would simply break service guarantees.
*
* To reduce this problem, push up a little bit the
* backshifted timestamps of the queue associated with this
* entity (only a queue can happen to have the backshifted
* flag set): just enough to let the finish timestamp of the
* queue be equal to the current value of the system virtual
* time. This may introduce a little unfairness among queues
* with backshifted timestamps, but it does not break
* worst-case fairness guarantees.
*
* As a special case, if bfqq is weight-raised, push up
* timestamps much less, to keep very low the probability that
* this push up causes the backshifted finish timestamps of
* weight-raised queues to become higher than the backshifted
* finish timestamps of non weight-raised queues.
*/
if (backshifted && bfq_gt(st->vtime, entity->finish)) {
unsigned long delta = st->vtime - entity->finish;
if (bfqq)
delta /= bfqq->wr_coeff;
entity->start += delta;
entity->finish += delta;
}
bfq_active_insert(st, entity);
}
/**
* __bfq_activate_entity - handle activation of entity.
* @entity: the entity being activated.
* @non_blocking_wait_rq: true if entity was waiting for a request
*
* Called for a 'true' activation, i.e., if entity is not active and
* one of its children receives a new request.
*
* Basically, this function updates the timestamps of entity and
* inserts entity into its active tree, after possibly extracting it
* from its idle tree.
*/
static void __bfq_activate_entity(struct bfq_entity *entity,
bool non_blocking_wait_rq)
{
struct bfq_service_tree *st = bfq_entity_service_tree(entity);
bool backshifted = false;
unsigned long long min_vstart;
/* See comments on bfq_fqq_update_budg_for_activation */
if (non_blocking_wait_rq && bfq_gt(st->vtime, entity->finish)) {
backshifted = true;
min_vstart = entity->finish;
} else
min_vstart = st->vtime;
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(min_vstart, entity->finish) ?
min_vstart : 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 = min_vstart;
st->wsum += entity->weight;
/*
* entity is about to be inserted into a service tree,
* and then set in service: get a reference to make
* sure entity does not disappear until it is no
* longer in service or scheduled for service.
*/
bfq_get_entity(entity);
entity->on_st_or_in_serv = true;
}
bfq_update_fin_time_enqueue(entity, st, backshifted);
}
/**
* __bfq_requeue_entity - handle requeueing or repositioning of an entity.
* @entity: the entity being requeued or repositioned.
*
* Requeueing is needed if this entity stops being served, which
* happens if a leaf descendant entity has expired. On the other hand,
* repositioning is needed if the next_inservice_entity for the child
* entity has changed. See the comments inside the function for
* details.
*
* Basically, this function: 1) removes entity from its active tree if
* present there, 2) updates the timestamps of entity and 3) inserts
* entity back into its active tree (in the new, right position for
* the new values of the timestamps).
*/
static void __bfq_requeue_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) {
/*
* We are requeueing the current in-service entity,
* which may have to be done for one of the following
* reasons:
* - entity represents the in-service queue, and the
* in-service queue is being requeued after an
* expiration;
* - entity represents a group, and its budget has
* changed because one of its child entities has
* just been either activated or requeued for some
* reason; the timestamps of the entity need then to
* be updated, and the entity needs to be enqueued
* or repositioned accordingly.
*
* In particular, before requeueing, the start time of
* the entity must be moved forward to account for the
* service that the entity has received while in
* service. This is done by the next instructions. The
* finish time will then be updated according to this
* new value of the start time, and to the budget of
* the entity.
*/
bfq_calc_finish(entity, entity->service);
entity->start = entity->finish;
/*
* In addition, if the entity had more than one child
* when set in service, then it was not extracted from
* the active tree. This implies that the position of
* the entity in the active tree may need to be
* changed now, because we have just updated the start
* time of the entity, and we will update its finish
* time in a moment (the requeueing is then, more
* precisely, a repositioning in this case). To
* implement this repositioning, we: 1) dequeue the
* entity here, 2) update the finish time and requeue
* the entity according to the new timestamps below.
*/
if (entity->tree)
bfq_active_extract(st, entity);
} else { /* The entity is already active, and not in service */
/*
* In this case, this function gets called only if the
* next_in_service entity below this entity has
* changed, and this change has caused the budget of
* this entity to change, which, finally implies that
* the finish time of this entity must be
* updated. Such an update may cause the scheduling,
* i.e., the position in the active tree, of this
* entity to change. We handle this change by: 1)
* dequeueing the entity here, 2) updating the finish
* time and requeueing the entity according to the new
* timestamps below. This is the same approach as the
* non-extracted-entity sub-case above.
*/
bfq_active_extract(st, entity);
}
bfq_update_fin_time_enqueue(entity, st, false);
}
static void __bfq_activate_requeue_entity(struct bfq_entity *entity,
bool non_blocking_wait_rq)
{
struct bfq_service_tree *st = bfq_entity_service_tree(entity);
if (entity->sched_data->in_service_entity == entity ||
entity->tree == &st->active)
/*
* in service or already queued on the active tree,
* requeue or reposition
*/
__bfq_requeue_entity(entity);
else
/*
* Not in service and not queued on its active tree:
* the activity is idle and this is a true activation.
*/
__bfq_activate_entity(entity, non_blocking_wait_rq);
}
/**
* bfq_activate_requeue_entity - activate or requeue an entity representing a
* bfq_queue, and activate, requeue or reposition
* all ancestors for which such an update becomes
* necessary.
* @entity: the entity to activate.
* @non_blocking_wait_rq: true if this entity was waiting for a request
* @requeue: true if this is a requeue, which implies that bfqq is
* being expired; thus ALL its ancestors stop being served and must
* therefore be requeued
* @expiration: true if this function is being invoked in the expiration path
* of the in-service queue
*/
static void bfq_activate_requeue_entity(struct bfq_entity *entity,
bool non_blocking_wait_rq,
bool requeue, bool expiration)
{
for_each_entity(entity) {
__bfq_activate_requeue_entity(entity, non_blocking_wait_rq);
if (!bfq_update_next_in_service(entity->sched_data, entity,
expiration) && !requeue)
break;
}
}
/**
* __bfq_deactivate_entity - update sched_data and service trees for
* entity, so as to represent entity as inactive
* @entity: the entity being deactivated.
* @ins_into_idle_tree: if false, the entity will not be put into the
* idle tree.
*
* If necessary and allowed, puts entity into the idle tree. NOTE:
* entity may be on no tree if in service.
*/
bool __bfq_deactivate_entity(struct bfq_entity *entity, bool ins_into_idle_tree)
{
struct bfq_sched_data *sd = entity->sched_data;
struct bfq_service_tree *st;
bool is_in_service;
if (!entity->on_st_or_in_serv) /*
* entity never activated, or
* already inactive
*/
return false;
/*
* If we get here, then entity is active, which implies that
* bfq_group_set_parent has already been invoked for the group
* represented by entity. Therefore, the field
* entity->sched_data has been set, and we can safely use it.
*/
st = bfq_entity_service_tree(entity);
is_in_service = entity == sd->in_service_entity;
bfq_calc_finish(entity, entity->service);
if (is_in_service)
sd->in_service_entity = NULL;
else
/*
* Non in-service entity: nobody will take care of
* resetting its service counter on expiration. Do it
* now.
*/
entity->service = 0;
if (entity->tree == &st->active)
bfq_active_extract(st, entity);
else if (!is_in_service && entity->tree == &st->idle)
bfq_idle_extract(st, entity);
if (!ins_into_idle_tree || !bfq_gt(entity->finish, st->vtime))
bfq_forget_entity(st, entity, is_in_service);
else
bfq_idle_insert(st, entity);
return true;
}
/**
* bfq_deactivate_entity - deactivate an entity representing a bfq_queue.
* @entity: the entity to deactivate.
* @ins_into_idle_tree: true if the entity can be put into the idle tree
* @expiration: true if this function is being invoked in the expiration path
* of the in-service queue
*/
static void bfq_deactivate_entity(struct bfq_entity *entity,
bool ins_into_idle_tree,
bool expiration)
{
struct bfq_sched_data *sd;
struct bfq_entity *parent = NULL;
for_each_entity_safe(entity, parent) {
sd = entity->sched_data;
if (!__bfq_deactivate_entity(entity, ins_into_idle_tree)) {
/*
* entity is not in any tree any more, so
* this deactivation is a no-op, and there is
* nothing to change for upper-level entities
* (in case of expiration, this can never
* happen).
*/
return;
}
if (sd->next_in_service == entity)
/*
* entity was the next_in_service entity,
* then, since entity has just been
* deactivated, a new one must be found.
*/
bfq_update_next_in_service(sd, NULL, expiration);
if (sd->next_in_service || sd->in_service_entity) {
/*
* The parent entity is still active, because
* either next_in_service or in_service_entity
* is not NULL. So, no further upwards
* deactivation must be performed. Yet,
* next_in_service has changed. Then the
* schedule does need to be updated upwards.
*
* NOTE If in_service_entity is not NULL, then
* next_in_service may happen to be NULL,
* although the parent entity is evidently
* active. This happens if 1) the entity
* pointed by in_service_entity is the only
* active entity in the parent entity, and 2)
* according to the definition of
* next_in_service, the in_service_entity
* cannot be considered as
* next_in_service. See the comments on the
* definition of next_in_service for details.
*/
break;
}
/*
* If we get here, then the parent is no more
* backlogged and we need to propagate the
* deactivation upwards. Thus let the loop go on.
*/
/*
* Also let parent be queued into the idle tree on
* deactivation, to preserve service guarantees, and
* assuming that who invoked this function does not
* need parent entities too to be removed completely.
*/
ins_into_idle_tree = true;
}
/*
* If the deactivation loop is fully executed, then there are
* no more entities to touch and next loop is not executed at
* all. Otherwise, requeue remaining entities if they are
* about to stop receiving service, or reposition them if this
* is not the case.
*/
entity = parent;
for_each_entity(entity) {
/*
* Invoke __bfq_requeue_entity on entity, even if
* already active, to requeue/reposition it in the
* active tree (because sd->next_in_service has
* changed)
*/
__bfq_requeue_entity(entity);
sd = entity->sched_data;
if (!bfq_update_next_in_service(sd, entity, expiration) &&
!expiration)
/*
* next_in_service unchanged or not causing
* any change in entity->parent->sd, and no
* requeueing needed for expiration: stop
* here.
*/
break;
}
}
/**
* bfq_calc_vtime_jump - compute the value to which the vtime should jump,
* if needed, to have at least one entity eligible.
* @st: the service tree to act upon.
*
* Assumes that st is not empty.
*/
static u64 bfq_calc_vtime_jump(struct bfq_service_tree *st)
{
struct bfq_entity *root_entity = bfq_root_active_entity(&st->active);
if (bfq_gt(root_entity->min_start, st->vtime))
return root_entity->min_start;
return st->vtime;
}
static void bfq_update_vtime(struct bfq_service_tree *st, u64 new_value)
{
if (new_value > st->vtime) {
st->vtime = new_value;
bfq_forget_idle(st);
}
}
/**
* bfq_first_active_entity - find the eligible entity with
* the smallest finish time
* @st: the service tree to select from.
* @vtime: the system virtual to use as a reference for eligibility
*
* 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,
u64 vtime)
{
struct bfq_entity *entry, *first = NULL;
struct rb_node *node = st->active.rb_node;
while (node) {
entry = rb_entry(node, struct bfq_entity, rb_node);
left:
if (!bfq_gt(entry->start, vtime))
first = entry;
if (node->rb_left) {
entry = rb_entry(node->rb_left,
struct bfq_entity, rb_node);
if (!bfq_gt(entry->min_start, vtime)) {
node = node->rb_left;
goto left;
}
}
if (first)
break;
node = node->rb_right;
}
return first;
}
/**
* __bfq_lookup_next_entity - return the first eligible entity in @st.
* @st: the service tree.
* @in_service: whether or not there is an in-service entity for the sched_data
* this active tree belongs to.
*
* If there is no in-service entity for the sched_data st belongs to,
* then return the entity that will be set in service if:
* 1) the parent entity this st belongs to is set in service;
* 2) no entity belonging to such parent entity undergoes a state change
* that would influence the timestamps of the entity (e.g., becomes idle,
* becomes backlogged, changes its budget, ...).
*
* In this first case, update the virtual time in @st too (see the
* comments on this update inside the function).
*
* In contrast, if there is an in-service entity, then return the
* entity that would be set in service if not only the above
* conditions, but also the next one held true: the currently
* in-service entity, on expiration,
* 1) gets a finish time equal to the current one, or
* 2) is not eligible any more, or
* 3) is idle.
*/
static struct bfq_entity *
__bfq_lookup_next_entity(struct bfq_service_tree *st, bool in_service)
{
struct bfq_entity *entity;
u64 new_vtime;
if (RB_EMPTY_ROOT(&st->active))
return NULL;
/*
* Get the value of the system virtual time for which at
* least one entity is eligible.
*/
new_vtime = bfq_calc_vtime_jump(st);
/*
* If there is no in-service entity for the sched_data this
* active tree belongs to, then push the system virtual time
* up to the value that guarantees that at least one entity is
* eligible. If, instead, there is an in-service entity, then
* do not make any such update, because there is already an
* eligible entity, namely the in-service one (even if the
* entity is not on st, because it was extracted when set in
* service).
*/
if (!in_service)
bfq_update_vtime(st, new_vtime);
entity = bfq_first_active_entity(st, new_vtime);
return entity;
}
/**
* bfq_lookup_next_entity - return the first eligible entity in @sd.
* @sd: the sched_data.
* @expiration: true if we are on the expiration path of the in-service queue
*
* This function is invoked when there has been a change in the trees
* for sd, and we need to know what is the new next entity to serve
* after this change.
*/
static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
bool expiration)
{
struct bfq_service_tree *st = sd->service_tree;
struct bfq_service_tree *idle_class_st = st + (BFQ_IOPRIO_CLASSES - 1);
struct bfq_entity *entity = NULL;
int class_idx = 0;
/*
* Choose from idle class, if needed to guarantee a minimum
* bandwidth to this class (and if there is some active entity
* in idle class). This should also mitigate
* priority-inversion problems in case a low priority task is
* holding file system resources.
*/
if (time_is_before_jiffies(sd->bfq_class_idle_last_service +
BFQ_CL_IDLE_TIMEOUT)) {
if (!RB_EMPTY_ROOT(&idle_class_st->active))
class_idx = BFQ_IOPRIO_CLASSES - 1;
/* About to be served if backlogged, or not yet backlogged */
sd->bfq_class_idle_last_service = jiffies;
}
/*
* Find the next entity to serve for the highest-priority
* class, unless the idle class needs to be served.
*/
for (; class_idx < BFQ_IOPRIO_CLASSES; class_idx++) {
/*
* If expiration is true, then bfq_lookup_next_entity
* is being invoked as a part of the expiration path
* of the in-service queue. In this case, even if
* sd->in_service_entity is not NULL,
* sd->in_service_entity at this point is actually not
* in service any more, and, if needed, has already
* been properly queued or requeued into the right
* tree. The reason why sd->in_service_entity is still
* not NULL here, even if expiration is true, is that
* sd->in_service_entity is reset as a last step in the
* expiration path. So, if expiration is true, tell
* __bfq_lookup_next_entity that there is no
* sd->in_service_entity.
*/
entity = __bfq_lookup_next_entity(st + class_idx,
sd->in_service_entity &&
!expiration);
if (entity)
break;
}
return entity;
}
bool next_queue_may_preempt(struct bfq_data *bfqd)
{
struct bfq_sched_data *sd = &bfqd->root_group->sched_data;
return sd->next_in_service != sd->in_service_entity;
}
/*
* Get next queue for service.
*/
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;
if (bfq_tot_busy_queues(bfqd) == 0)
return NULL;
/*
* Traverse the path from the root to the leaf entity to
* serve. Set in service all the entities visited along the
* way.
*/
sd = &bfqd->root_group->sched_data;
for (; sd ; sd = entity->my_sched_data) {
/*
* WARNING. We are about to set the in-service entity
* to sd->next_in_service, i.e., to the (cached) value
* returned by bfq_lookup_next_entity(sd) the last
* time it was invoked, i.e., the last time when the
* service order in sd changed as a consequence of the
* activation or deactivation of an entity. In this
* respect, if we execute bfq_lookup_next_entity(sd)
* in this very moment, it may, although with low
* probability, yield a different entity than that
* pointed to by sd->next_in_service. This rare event
* happens in case there was no CLASS_IDLE entity to
* serve for sd when bfq_lookup_next_entity(sd) was
* invoked for the last time, while there is now one
* such entity.
*
* If the above event happens, then the scheduling of
* such entity in CLASS_IDLE is postponed until the
* service of the sd->next_in_service entity
* finishes. In fact, when the latter is expired,
* bfq_lookup_next_entity(sd) gets called again,
* exactly to update sd->next_in_service.
*/
/* Make next_in_service entity become in_service_entity */
entity = sd->next_in_service;
sd->in_service_entity = entity;
/*
* If entity is no longer a candidate for next
* service, then it must be extracted from its active
* tree, so as to make sure that it won't be
* considered when computing next_in_service. See the
* comments on the function
* bfq_no_longer_next_in_service() for details.
*/
if (bfq_no_longer_next_in_service(entity))
bfq_active_extract(bfq_entity_service_tree(entity),
entity);
/*
* Even if entity is not to be extracted according to
* the above check, a descendant entity may get
* extracted in one of the next iterations of this
* loop. Such an event could cause a change in
* next_in_service for the level of the descendant
* entity, and thus possibly back to this level.
*
* However, we cannot perform the resulting needed
* update of next_in_service for this level before the
* end of the whole loop, because, to know which is
* the correct next-to-serve candidate entity for each
* level, we need first to find the leaf entity to set
* in service. In fact, only after we know which is
* the next-to-serve leaf entity, we can discover
* whether the parent entity of the leaf entity
* becomes the next-to-serve, and so on.
*/
}
bfqq = bfq_entity_to_bfqq(entity);
/*
* We can finally update all next-to-serve entities along the
* path from the leaf entity just set in service to the root.
*/
for_each_entity(entity) {
struct bfq_sched_data *sd = entity->sched_data;
if (!bfq_update_next_in_service(sd, NULL, false))
break;
}
return bfqq;
}
/* returns true if the in-service queue gets freed */
bool __bfq_bfqd_reset_in_service(struct bfq_data *bfqd)
{
struct bfq_queue *in_serv_bfqq = bfqd->in_service_queue;
struct bfq_entity *in_serv_entity = &in_serv_bfqq->entity;
struct bfq_entity *entity = in_serv_entity;
bfq_clear_bfqq_wait_request(in_serv_bfqq);
hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
bfqd->in_service_queue = NULL;
/*
* When this function is called, all in-service entities have
* been properly deactivated or requeued, so we can safely
* execute the final step: reset in_service_entity along the
* path from entity to the root.
*/
for_each_entity(entity)
entity->sched_data->in_service_entity = NULL;
/*
* in_serv_entity is no longer in service, so, if it is in no
* service tree either, then release the service reference to
* the queue it represents (taken with bfq_get_entity).
*/
if (!in_serv_entity->on_st_or_in_serv) {
/*
* If no process is referencing in_serv_bfqq any
* longer, then the service reference may be the only
* reference to the queue. If this is the case, then
* bfqq gets freed here.
*/
int ref = in_serv_bfqq->ref;
bfq_put_queue(in_serv_bfqq);
if (ref == 1)
return true;
}
return false;
}
void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
bool ins_into_idle_tree, bool expiration)
{
struct bfq_entity *entity = &bfqq->entity;
bfq_deactivate_entity(entity, ins_into_idle_tree, expiration);
}
void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
{
struct bfq_entity *entity = &bfqq->entity;
bfq_activate_requeue_entity(entity, bfq_bfqq_non_blocking_wait_rq(bfqq),
false, false);
bfq_clear_bfqq_non_blocking_wait_rq(bfqq);
}
void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
bool expiration)
{
struct bfq_entity *entity = &bfqq->entity;
bfq_activate_requeue_entity(entity, false,
bfqq == bfqd->in_service_queue, expiration);
}
void bfq_add_bfqq_in_groups_with_pending_reqs(struct bfq_queue *bfqq)
{
#ifdef CONFIG_BFQ_GROUP_IOSCHED
struct bfq_entity *entity = &bfqq->entity;
if (!entity->in_groups_with_pending_reqs) {
entity->in_groups_with_pending_reqs = true;
if (!(bfqq_group(bfqq)->num_queues_with_pending_reqs++))
bfqq->bfqd->num_groups_with_pending_reqs++;
}
#endif
}
void bfq_del_bfqq_in_groups_with_pending_reqs(struct bfq_queue *bfqq)
{
#ifdef CONFIG_BFQ_GROUP_IOSCHED
struct bfq_entity *entity = &bfqq->entity;
if (entity->in_groups_with_pending_reqs) {
entity->in_groups_with_pending_reqs = false;
if (!(--bfqq_group(bfqq)->num_queues_with_pending_reqs))
bfqq->bfqd->num_groups_with_pending_reqs--;
}
#endif
}
/*
* Called when the bfqq no longer has requests pending, remove it from
* the service tree. As a special case, it can be invoked during an
* expiration.
*/
void bfq_del_bfqq_busy(struct bfq_queue *bfqq, bool expiration)
{
struct bfq_data *bfqd = bfqq->bfqd;
bfq_log_bfqq(bfqd, bfqq, "del from busy");
bfq_clear_bfqq_busy(bfqq);
bfqd->busy_queues[bfqq->ioprio_class - 1]--;
if (bfqq->wr_coeff > 1)
bfqd->wr_busy_queues--;
bfqg_stats_update_dequeue(bfqq_group(bfqq));
bfq_deactivate_bfqq(bfqd, bfqq, true, expiration);
if (!bfqq->dispatched) {
bfq_del_bfqq_in_groups_with_pending_reqs(bfqq);
/*
* Next function is invoked last, because it causes bfqq to be
* freed. DO NOT use bfqq after the next function invocation.
*/
bfq_weights_tree_remove(bfqq);
}
}
/*
* Called when an inactive queue receives a new request.
*/
void bfq_add_bfqq_busy(struct bfq_queue *bfqq)
{
struct bfq_data *bfqd = bfqq->bfqd;
bfq_log_bfqq(bfqd, bfqq, "add to busy");
bfq_activate_bfqq(bfqd, bfqq);
bfq_mark_bfqq_busy(bfqq);
bfqd->busy_queues[bfqq->ioprio_class - 1]++;
if (!bfqq->dispatched) {
bfq_add_bfqq_in_groups_with_pending_reqs(bfqq);
if (bfqq->wr_coeff == 1)
bfq_weights_tree_add(bfqq);
}
if (bfqq->wr_coeff > 1)
bfqd->wr_busy_queues++;
/* Move bfqq to the head of the woken list of its waker */
if (!hlist_unhashed(&bfqq->woken_list_node) &&
&bfqq->woken_list_node != bfqq->waker_bfqq->woken_list.first) {
hlist_del_init(&bfqq->woken_list_node);
hlist_add_head(&bfqq->woken_list_node,
&bfqq->waker_bfqq->woken_list);
}
}
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