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SubjectRe: [PATCH] block, bfq: improve asymmetric scenarios detection
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Date
Hi Jens,
this is based against next, and meant for 4.20, if we are not too late
again (and, of course, if the patch is acceptable).

Thanks,
Paolo

> Il giorno 12 ott 2018, alle ore 11:55, Paolo Valente <paolo.valente@linaro.org> ha scritto:
>
> From: Federico Motta <federico@willer.it>
>
> bfq defines as asymmetric a scenario where an active entity, say E
> (representing either a single bfq_queue or a group of other entities),
> has a higher weight than some other entities. If the entity E does sync
> I/O in such a scenario, then bfq plugs the dispatch of the I/O of the
> other entities in the following situation: E is in service but
> temporarily has no pending I/O request. In fact, without this plugging,
> all the times that E stops being temporarily idle, it may find the
> internal queues of the storage device already filled with an
> out-of-control number of extra requests, from other entities. So E may
> have to wait for the service of these extra requests, before finally
> having its own requests served. This may easily break service
> guarantees, with E getting less than its fair share of the device
> throughput. Usually, the end result is that E gets the same fraction of
> the throughput as the other entities, instead of getting more, according
> to its higher weight.
>
> Yet there are two other more subtle cases where E, even if its weight is
> actually equal to or even lower than the weight of any other active
> entities, may get less than its fair share of the throughput in case the
> above I/O plugging is not performed:
> 1. other entities issue larger requests than E;
> 2. other entities contain more active child entities than E (or in
> general tend to have more backlog than E).
>
> In the first case, other entities may get more service than E because
> they get larger requests, than those of E, served during the temporary
> idle periods of E. In the second case, other entities get more service
> because, by having many child entities, they have many requests ready
> for dispatching while E is temporarily idle.
>
> This commit addresses this issue by extending the definition of
> asymmetric scenario: a scenario is asymmetric when
> - active entities representing bfq_queues have differentiated weights,
> as in the original definition
> or (inclusive)
> - one or more entities representing groups of entities are active.
>
> This broader definition makes sure that I/O plugging will be performed
> in all the above cases, provided that there is at least one active
> group. Of course, this definition is very coarse, so it will trigger
> I/O plugging also in cases where it is not needed, such as, e.g.,
> multiple active entities with just one child each, and all with the same
> I/O-request size. The reason for this coarse definition is just that a
> finer-grained definition would be rather heavy to compute.
>
> On the opposite end, even this new definition does not trigger I/O
> plugging in all cases where there is no active group, and all bfq_queues
> have the same weight. So, in these cases some unfairness may occur if
> there are asymmetries in I/O-request sizes. We made this choice because
> I/O plugging may lower throughput, and probably a user that has not
> created any group cares more about throughput than about perfect
> fairness. At any rate, as for possible applications that may care about
> service guarantees, bfq already guarantees a high responsiveness and a
> low latency to soft real-time applications automatically.
>
> Signed-off-by: Federico Motta <federico@willer.it>
> Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
> ---
> block/bfq-iosched.c | 223 ++++++++++++++++++++++++--------------------
> block/bfq-iosched.h | 27 +++---
> block/bfq-wf2q.c | 36 +++----
> 3 files changed, 155 insertions(+), 131 deletions(-)
>
> diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
> index 1a1b80dfd69d..6075100f03a5 100644
> --- a/block/bfq-iosched.c
> +++ b/block/bfq-iosched.c
> @@ -624,12 +624,13 @@ void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq)
> }
>
> /*
> - * Tell whether there are active queues or groups with differentiated weights.
> + * Tell whether there are active queues with different weights or
> + * active groups.
> */
> -static bool bfq_differentiated_weights(struct bfq_data *bfqd)
> +static bool bfq_varied_queue_weights_or_active_groups(struct bfq_data *bfqd)
> {
> /*
> - * For weights to differ, at least one of the trees must contain
> + * For queue weights to differ, queue_weights_tree must contain
> * at least two nodes.
> */
> return (!RB_EMPTY_ROOT(&bfqd->queue_weights_tree) &&
> @@ -637,9 +638,7 @@ static bool bfq_differentiated_weights(struct bfq_data *bfqd)
> bfqd->queue_weights_tree.rb_node->rb_right)
> #ifdef CONFIG_BFQ_GROUP_IOSCHED
> ) ||
> - (!RB_EMPTY_ROOT(&bfqd->group_weights_tree) &&
> - (bfqd->group_weights_tree.rb_node->rb_left ||
> - bfqd->group_weights_tree.rb_node->rb_right)
> + (bfqd->num_active_groups > 0
> #endif
> );
> }
> @@ -657,26 +656,25 @@ static bool bfq_differentiated_weights(struct bfq_data *bfqd)
> * 3) all active groups at the same level in the groups tree have the same
> * number of children.
> *
> - * Unfortunately, keeping the necessary state for evaluating exactly the
> - * above symmetry conditions would be quite complex and time-consuming.
> - * Therefore this function evaluates, instead, the following stronger
> - * sub-conditions, for which it is much easier to maintain the needed
> - * state:
> + * Unfortunately, keeping the necessary state for evaluating exactly
> + * the last two symmetry sub-conditions above would be quite complex
> + * and time consuming. Therefore this function evaluates, instead,
> + * only the following stronger two sub-conditions, for which it is
> + * much easier to maintain the needed state:
> * 1) all active queues have the same weight,
> - * 2) all active groups have the same weight,
> - * 3) all active groups have at most one active child each.
> - * In particular, the last two conditions are always true if hierarchical
> - * support and the cgroups interface are not enabled, thus no state needs
> - * to be maintained in this case.
> + * 2) there are no active groups.
> + * In particular, the last condition is always true if hierarchical
> + * support or the cgroups interface are not enabled, thus no state
> + * needs to be maintained in this case.
> */
> static bool bfq_symmetric_scenario(struct bfq_data *bfqd)
> {
> - return !bfq_differentiated_weights(bfqd);
> + return !bfq_varied_queue_weights_or_active_groups(bfqd);
> }
>
> /*
> * If the weight-counter tree passed as input contains no counter for
> - * the weight of the input entity, then add that counter; otherwise just
> + * the weight of the input queue, then add that counter; otherwise just
> * increment the existing counter.
> *
> * Note that weight-counter trees contain few nodes in mostly symmetric
> @@ -687,25 +685,25 @@ static bool bfq_symmetric_scenario(struct bfq_data *bfqd)
> * In most scenarios, the rate at which nodes are created/destroyed
> * should be low too.
> */
> -void bfq_weights_tree_add(struct bfq_data *bfqd, struct bfq_entity *entity,
> +void bfq_weights_tree_add(struct bfq_data *bfqd, struct bfq_queue *bfqq,
> struct rb_root *root)
> {
> + struct bfq_entity *entity = &bfqq->entity;
> struct rb_node **new = &(root->rb_node), *parent = NULL;
>
> /*
> - * Do not insert if the entity is already associated with a
> + * Do not insert if the queue is already associated with a
> * counter, which happens if:
> - * 1) the entity is associated with a queue,
> - * 2) a request arrival has caused the queue to become both
> + * 1) a request arrival has caused the queue to become both
> * non-weight-raised, and hence change its weight, and
> * backlogged; in this respect, each of the two events
> * causes an invocation of this function,
> - * 3) this is the invocation of this function caused by the
> + * 2) this is the invocation of this function caused by the
> * second event. This second invocation is actually useless,
> * and we handle this fact by exiting immediately. More
> * efficient or clearer solutions might possibly be adopted.
> */
> - if (entity->weight_counter)
> + if (bfqq->weight_counter)
> return;
>
> while (*new) {
> @@ -715,7 +713,7 @@ void bfq_weights_tree_add(struct bfq_data *bfqd, struct bfq_entity *entity,
> parent = *new;
>
> if (entity->weight == __counter->weight) {
> - entity->weight_counter = __counter;
> + bfqq->weight_counter = __counter;
> goto inc_counter;
> }
> if (entity->weight < __counter->weight)
> @@ -724,66 +722,67 @@ void bfq_weights_tree_add(struct bfq_data *bfqd, struct bfq_entity *entity,
> new = &((*new)->rb_right);
> }
>
> - entity->weight_counter = kzalloc(sizeof(struct bfq_weight_counter),
> - GFP_ATOMIC);
> + bfqq->weight_counter = kzalloc(sizeof(struct bfq_weight_counter),
> + GFP_ATOMIC);
>
> /*
> * In the unlucky event of an allocation failure, we just
> - * exit. This will cause the weight of entity to not be
> - * considered in bfq_differentiated_weights, which, in its
> - * turn, causes the scenario to be deemed wrongly symmetric in
> - * case entity's weight would have been the only weight making
> - * the scenario asymmetric. On the bright side, no unbalance
> - * will however occur when entity becomes inactive again (the
> - * invocation of this function is triggered by an activation
> - * of entity). In fact, bfq_weights_tree_remove does nothing
> - * if !entity->weight_counter.
> + * exit. This will cause the weight of queue to not be
> + * considered in bfq_varied_queue_weights_or_active_groups,
> + * which, in its turn, causes the scenario to be deemed
> + * wrongly symmetric in case bfqq's weight would have been
> + * the only weight making the scenario asymmetric. On the
> + * bright side, no unbalance will however occur when bfqq
> + * becomes inactive again (the invocation of this function
> + * is triggered by an activation of queue). In fact,
> + * bfq_weights_tree_remove does nothing if
> + * !bfqq->weight_counter.
> */
> - if (unlikely(!entity->weight_counter))
> + if (unlikely(!bfqq->weight_counter))
> return;
>
> - entity->weight_counter->weight = entity->weight;
> - rb_link_node(&entity->weight_counter->weights_node, parent, new);
> - rb_insert_color(&entity->weight_counter->weights_node, root);
> + bfqq->weight_counter->weight = entity->weight;
> + rb_link_node(&bfqq->weight_counter->weights_node, parent, new);
> + rb_insert_color(&bfqq->weight_counter->weights_node, root);
>
> inc_counter:
> - entity->weight_counter->num_active++;
> + bfqq->weight_counter->num_active++;
> }
>
> /*
> - * Decrement the weight counter associated with the entity, and, if the
> + * Decrement the weight counter associated with the queue, and, if the
> * counter reaches 0, remove the counter from the tree.
> * See the comments to the function bfq_weights_tree_add() for considerations
> * about overhead.
> */
> void __bfq_weights_tree_remove(struct bfq_data *bfqd,
> - struct bfq_entity *entity,
> + struct bfq_queue *bfqq,
> struct rb_root *root)
> {
> - if (!entity->weight_counter)
> + if (!bfqq->weight_counter)
> return;
>
> - entity->weight_counter->num_active--;
> - if (entity->weight_counter->num_active > 0)
> + bfqq->weight_counter->num_active--;
> + if (bfqq->weight_counter->num_active > 0)
> goto reset_entity_pointer;
>
> - rb_erase(&entity->weight_counter->weights_node, root);
> - kfree(entity->weight_counter);
> + rb_erase(&bfqq->weight_counter->weights_node, root);
> + kfree(bfqq->weight_counter);
>
> reset_entity_pointer:
> - entity->weight_counter = NULL;
> + bfqq->weight_counter = NULL;
> }
>
> /*
> - * Invoke __bfq_weights_tree_remove on bfqq and all its inactive
> - * parent entities.
> + * Invoke __bfq_weights_tree_remove on bfqq and decrement the number
> + * of active groups for each queue's inactive parent entity.
> */
> void bfq_weights_tree_remove(struct bfq_data *bfqd,
> struct bfq_queue *bfqq)
> {
> struct bfq_entity *entity = bfqq->entity.parent;
>
> - __bfq_weights_tree_remove(bfqd, &bfqq->entity,
> + __bfq_weights_tree_remove(bfqd, bfqq,
> &bfqd->queue_weights_tree);
>
> for_each_entity(entity) {
> @@ -797,17 +796,13 @@ void bfq_weights_tree_remove(struct bfq_data *bfqd,
> * next_in_service for details on why
> * in_service_entity must be checked too).
> *
> - * As a consequence, the weight of entity is
> - * not to be removed. In addition, if entity
> - * is active, then its parent entities are
> - * active as well, and thus their weights are
> - * not to be removed either. In the end, this
> - * loop must stop here.
> + * As a consequence, its parent entities are
> + * active as well, and thus this loop must
> + * stop here.
> */
> break;
> }
> - __bfq_weights_tree_remove(bfqd, entity,
> - &bfqd->group_weights_tree);
> + bfqd->num_active_groups--;
> }
> }
>
> @@ -3506,9 +3501,11 @@ static bool bfq_better_to_idle(struct bfq_queue *bfqq)
> * symmetric scenario where:
> * (i) each of these processes must get the same throughput as
> * the others;
> - * (ii) all these processes have the same I/O pattern
> - (either sequential or random).
> - * In fact, in such a scenario, the drive will tend to treat
> + * (ii) the I/O of each process has the same properties, in
> + * terms of locality (sequential or random), direction
> + * (reads or writes), request sizes, greediness
> + * (from I/O-bound to sporadic), and so on.
> + * In fact, in such a scenario, the drive tends to treat
> * the requests of each of these processes in about the same
> * way as the requests of the others, and thus to provide
> * each of these processes with about the same throughput
> @@ -3517,18 +3514,50 @@ static bool bfq_better_to_idle(struct bfq_queue *bfqq)
> * certainly needed to guarantee that bfqq receives its
> * assigned fraction of the device throughput (see [1] for
> * details).
> + * The problem is that idling may significantly reduce
> + * throughput with certain combinations of types of I/O and
> + * devices. An important example is sync random I/O, on flash
> + * storage with command queueing. So, unless bfqq falls in the
> + * above cases where idling also boosts throughput, it would
> + * be important to check conditions (i) and (ii) accurately,
> + * so as to avoid idling when not strictly needed for service
> + * guarantees.
> + *
> + * Unfortunately, it is extremely difficult to thoroughly
> + * check condition (ii). And, in case there are active groups,
> + * it becomes very difficult to check condition (i) too. In
> + * fact, if there are active groups, then, for condition (i)
> + * to become false, it is enough that an active group contains
> + * more active processes or sub-groups than some other active
> + * group. We address this issue with the following bi-modal
> + * behavior, implemented in the function
> + * bfq_symmetric_scenario().
> *
> - * We address this issue by controlling, actually, only the
> - * symmetry sub-condition (i), i.e., provided that
> - * sub-condition (i) holds, idling is not performed,
> - * regardless of whether sub-condition (ii) holds. In other
> - * words, only if sub-condition (i) holds, then idling is
> + * If there are active groups, then the scenario is tagged as
> + * asymmetric, conservatively, without checking any of the
> + * conditions (i) and (ii). So the device is idled for bfqq.
> + * This behavior matches also the fact that groups are created
> + * exactly if controlling I/O (to preserve bandwidth and
> + * latency guarantees) is a primary concern.
> + *
> + * On the opposite end, if there are no active groups, then
> + * only condition (i) is actually controlled, i.e., provided
> + * that condition (i) holds, idling is not performed,
> + * regardless of whether condition (ii) holds. In other words,
> + * only if condition (i) does not hold, then idling is
> * allowed, and the device tends to be prevented from queueing
> - * many requests, possibly of several processes. The reason
> - * for not controlling also sub-condition (ii) is that we
> - * exploit preemption to preserve guarantees in case of
> - * symmetric scenarios, even if (ii) does not hold, as
> - * explained in the next two paragraphs.
> + * many requests, possibly of several processes. Since there
> + * are no active groups, then, to control condition (i) it is
> + * enough to check whether all active queues have the same
> + * weight.
> + *
> + * Not checking condition (ii) evidently exposes bfqq to the
> + * risk of getting less throughput than its fair share.
> + * However, for queues with the same weight, a further
> + * mechanism, preemption, mitigates or even eliminates this
> + * problem. And it does so without consequences on overall
> + * throughput. This mechanism and its benefits are explained
> + * in the next three paragraphs.
> *
> * Even if a queue, say Q, is expired when it remains idle, Q
> * can still preempt the new in-service queue if the next
> @@ -3542,11 +3571,7 @@ static bool bfq_better_to_idle(struct bfq_queue *bfqq)
> * idling allows the internal queues of the device to contain
> * many requests, and thus to reorder requests, we can rather
> * safely assume that the internal scheduler still preserves a
> - * minimum of mid-term fairness. The motivation for using
> - * preemption instead of idling is that, by not idling,
> - * service guarantees are preserved without minimally
> - * sacrificing throughput. In other words, both a high
> - * throughput and its desired distribution are obtained.
> + * minimum of mid-term fairness.
> *
> * More precisely, this preemption-based, idleless approach
> * provides fairness in terms of IOPS, and not sectors per
> @@ -3565,27 +3590,27 @@ static bool bfq_better_to_idle(struct bfq_queue *bfqq)
> * 1024/8 times as high as the service received by the other
> * queue.
> *
> - * On the other hand, device idling is performed, and thus
> - * pure sector-domain guarantees are provided, for the
> - * following queues, which are likely to need stronger
> - * throughput guarantees: weight-raised queues, and queues
> - * with a higher weight than other queues. When such queues
> - * are active, sub-condition (i) is false, which triggers
> - * device idling.
> + * The motivation for using preemption instead of idling (for
> + * queues with the same weight) is that, by not idling,
> + * service guarantees are preserved (completely or at least in
> + * part) without minimally sacrificing throughput. And, if
> + * there is no active group, then the primary expectation for
> + * this device is probably a high throughput.
> *
> - * According to the above considerations, the next variable is
> - * true (only) if sub-condition (i) holds. To compute the
> - * value of this variable, we not only use the return value of
> - * the function bfq_symmetric_scenario(), but also check
> - * whether bfqq is being weight-raised, because
> - * bfq_symmetric_scenario() does not take into account also
> - * weight-raised queues (see comments on
> - * bfq_weights_tree_add()). In particular, if bfqq is being
> - * weight-raised, it is important to idle only if there are
> - * other, non-weight-raised queues that may steal throughput
> - * to bfqq. Actually, we should be even more precise, and
> - * differentiate between interactive weight raising and
> - * soft real-time weight raising.
> + * We are now left only with explaining the additional
> + * compound condition that is checked below for deciding
> + * whether the scenario is asymmetric. To explain this
> + * compound condition, we need to add that the function
> + * bfq_symmetric_scenario checks the weights of only
> + * non-weight-raised queues, for efficiency reasons (see
> + * comments on bfq_weights_tree_add()). Then the fact that
> + * bfqq is weight-raised is checked explicitly here. More
> + * precisely, the compound condition below takes into account
> + * also the fact that, even if bfqq is being weight-raised,
> + * the scenario is still symmetric if all active queues happen
> + * to be weight-raised. Actually, we should be even more
> + * precise here, and differentiate between interactive weight
> + * raising and soft real-time weight raising.
> *
> * As a side note, it is worth considering that the above
> * device-idling countermeasures may however fail in the
> @@ -5392,7 +5417,7 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
> bfqd->idle_slice_timer.function = bfq_idle_slice_timer;
>
> bfqd->queue_weights_tree = RB_ROOT;
> - bfqd->group_weights_tree = RB_ROOT;
> + bfqd->num_active_groups = 0;
>
> INIT_LIST_HEAD(&bfqd->active_list);
> INIT_LIST_HEAD(&bfqd->idle_list);
> diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
> index 37d627afdc2e..77651d817ecd 100644
> --- a/block/bfq-iosched.h
> +++ b/block/bfq-iosched.h
> @@ -108,15 +108,14 @@ struct bfq_sched_data {
> };
>
> /**
> - * struct bfq_weight_counter - counter of the number of all active entities
> + * struct bfq_weight_counter - counter of the number of all active queues
> * with a given weight.
> */
> struct bfq_weight_counter {
> - unsigned int weight; /* weight of the entities this counter refers to */
> - unsigned int num_active; /* nr of active entities with this weight */
> + unsigned int weight; /* weight of the queues this counter refers to */
> + unsigned int num_active; /* nr of active queues with this weight */
> /*
> - * Weights tree member (see bfq_data's @queue_weights_tree and
> - * @group_weights_tree)
> + * Weights tree member (see bfq_data's @queue_weights_tree)
> */
> struct rb_node weights_node;
> };
> @@ -151,8 +150,6 @@ struct bfq_weight_counter {
> struct bfq_entity {
> /* service_tree member */
> struct rb_node rb_node;
> - /* pointer to the weight counter associated with this entity */
> - struct bfq_weight_counter *weight_counter;
>
> /*
> * Flag, true if the entity is on a tree (either the active or
> @@ -266,6 +263,9 @@ struct bfq_queue {
> /* entity representing this queue in the scheduler */
> struct bfq_entity entity;
>
> + /* pointer to the weight counter associated with this entity */
> + struct bfq_weight_counter *weight_counter;
> +
> /* maximum budget allowed from the feedback mechanism */
> int max_budget;
> /* budget expiration (in jiffies) */
> @@ -449,14 +449,9 @@ struct bfq_data {
> */
> struct rb_root queue_weights_tree;
> /*
> - * rbtree of non-queue @bfq_entity weight counters, sorted by
> - * weight. Used to keep track of whether all @bfq_groups have
> - * the same weight. The tree contains one counter for each
> - * distinct weight associated to some active @bfq_group (see
> - * the comments to the functions bfq_weights_tree_[add|remove]
> - * for further details).
> + * number of groups with requests still waiting for completion
> */
> - struct rb_root group_weights_tree;
> + unsigned int num_active_groups;
>
> /*
> * Number of bfq_queues containing requests (including the
> @@ -851,10 +846,10 @@ struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync);
> void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, bool is_sync);
> struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic);
> void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq);
> -void bfq_weights_tree_add(struct bfq_data *bfqd, struct bfq_entity *entity,
> +void bfq_weights_tree_add(struct bfq_data *bfqd, struct bfq_queue *bfqq,
> struct rb_root *root);
> void __bfq_weights_tree_remove(struct bfq_data *bfqd,
> - struct bfq_entity *entity,
> + struct bfq_queue *bfqq,
> struct rb_root *root);
> void bfq_weights_tree_remove(struct bfq_data *bfqd,
> struct bfq_queue *bfqq);
> diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c
> index ff7c2d470bb8..476b5a90a5a4 100644
> --- a/block/bfq-wf2q.c
> +++ b/block/bfq-wf2q.c
> @@ -788,25 +788,29 @@ __bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
> new_weight = entity->orig_weight *
> (bfqq ? 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 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) {
> - root = bfqq ? &bfqd->queue_weights_tree :
> - &bfqd->group_weights_tree;
> - __bfq_weights_tree_remove(bfqd, entity, root);
> + if (bfqq) {
> + root = &bfqd->queue_weights_tree;
> + __bfq_weights_tree_remove(bfqd, bfqq, root);
> + } else
> + bfqd->num_active_groups--;
> }
> entity->weight = new_weight;
> /*
> - * Add the entity to its weights tree only if it is
> - * not associated with a weight-raised queue.
> + * 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 : 1))
> - /* If we get here, root has been initialized. */
> - bfq_weights_tree_add(bfqd, entity, root);
> + if (prev_weight != new_weight) {
> + if (bfqq && bfqq->wr_coeff == 1) {
> + /* If we get here, root has been initialized. */
> + bfq_weights_tree_add(bfqd, bfqq, root);
> + } else
> + bfqd->num_active_groups++;
> + }
>
> new_st->wsum += entity->weight;
>
> @@ -1012,9 +1016,9 @@ static void __bfq_activate_entity(struct bfq_entity *entity,
> if (!bfq_entity_to_bfqq(entity)) { /* bfq_group */
> struct bfq_group *bfqg =
> container_of(entity, struct bfq_group, entity);
> + struct bfq_data *bfqd = bfqg->bfqd;
>
> - bfq_weights_tree_add(bfqg->bfqd, entity,
> - &bfqd->group_weights_tree);
> + bfqd->num_active_groups++;
> }
> #endif
>
> @@ -1692,7 +1696,7 @@ void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq)
>
> if (!bfqq->dispatched)
> if (bfqq->wr_coeff == 1)
> - bfq_weights_tree_add(bfqd, &bfqq->entity,
> + bfq_weights_tree_add(bfqd, bfqq,
> &bfqd->queue_weights_tree);
>
> if (bfqq->wr_coeff > 1)
> --
> 2.19.1
>

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