diff options
| -rw-r--r-- | block/bfq-iosched.c | 14 | ||||
| -rw-r--r-- | block/bfq-iosched.h | 3 | ||||
| -rw-r--r-- | block/bfq-wf2q.c | 39 |
3 files changed, 46 insertions, 10 deletions
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 12bbc6b8657d..60a6835265fc 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -3483,11 +3483,17 @@ static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq) } } } - /* Update weight both if it must be raised and if it must be lowered */ + /* + * To improve latency (for this or other queues), immediately + * update weight both if it must be raised and if it must be + * lowered. Since, entity may be on some active tree here, and + * might have a pending change of its ioprio class, invoke + * next function with the last parameter unset (see the + * comments on the function). + */ if ((entity->weight > entity->orig_weight) != (bfqq->wr_coeff > 1)) - __bfq_entity_update_weight_prio( - bfq_entity_service_tree(entity), - entity); + __bfq_entity_update_weight_prio(bfq_entity_service_tree(entity), + entity, false); } /* diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h index 5c3bf9861492..8fd83b885774 100644 --- a/block/bfq-iosched.h +++ b/block/bfq-iosched.h @@ -892,7 +892,8 @@ void bfq_put_idle_entity(struct bfq_service_tree *st, struct bfq_entity *entity); struct bfq_service_tree * __bfq_entity_update_weight_prio(struct bfq_service_tree *old_st, - struct bfq_entity *entity); + struct bfq_entity *entity, + bool update_class_too); void bfq_bfqq_served(struct bfq_queue *bfqq, int served); void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq, unsigned long time_ms); diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c index 8726ede19eef..5ec05cd42b80 100644 --- a/block/bfq-wf2q.c +++ b/block/bfq-wf2q.c @@ -694,10 +694,28 @@ struct bfq_service_tree *bfq_entity_service_tree(struct bfq_entity *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) + struct bfq_entity *entity, + bool update_class_too) { struct bfq_service_tree *new_st = old_st; @@ -739,9 +757,15 @@ __bfq_entity_update_weight_prio(struct bfq_service_tree *old_st, bfq_weight_to_ioprio(entity->orig_weight); } - if (bfqq) + if (bfqq && update_class_too) bfqq->ioprio_class = bfqq->new_ioprio_class; - entity->prio_changed = 0; + + /* + * 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, @@ -867,7 +891,12 @@ static void bfq_update_fin_time_enqueue(struct bfq_entity *entity, { struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); - st = __bfq_entity_update_weight_prio(st, 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); /* |