diff options
Diffstat (limited to 'block')
| -rw-r--r-- | block/cfq-iosched.c | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 175218d66d6..7701c3fe49b 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -225,6 +225,18 @@ struct cfq_group { u64 vdisktime; /* + * The number of active cfqgs and sum of their weights under this + * cfqg. This covers this cfqg's leaf_weight and all children's + * weights, but does not cover weights of further descendants. + * + * If a cfqg is on the service tree, it's active. An active cfqg + * also activates its parent and contributes to the children_weight + * of the parent. + */ + int nr_active; + unsigned int children_weight; + + /* * There are two weights - (internal) weight is the weight of this * cfqg against the sibling cfqgs. leaf_weight is the wight of * this cfqg against the child cfqgs. For the root cfqg, both @@ -583,6 +595,22 @@ static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg) return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq)); } +/* + * Determine the parent cfqg for weight calculation. Currently, cfqg + * scheduling is flat and the root is the parent of everyone else. + */ +static inline struct cfq_group *cfqg_flat_parent(struct cfq_group *cfqg) +{ + struct blkcg_gq *blkg = cfqg_to_blkg(cfqg); + struct cfq_group *root; + + while (blkg->parent) + blkg = blkg->parent; + root = blkg_to_cfqg(blkg); + + return root != cfqg ? root : NULL; +} + static inline void cfqg_get(struct cfq_group *cfqg) { return blkg_get(cfqg_to_blkg(cfqg)); @@ -683,6 +711,7 @@ static void cfq_pd_reset_stats(struct blkcg_gq *blkg) #else /* CONFIG_CFQ_GROUP_IOSCHED */ +static inline struct cfq_group *cfqg_flat_parent(struct cfq_group *cfqg) { return NULL; } static inline void cfqg_get(struct cfq_group *cfqg) { } static inline void cfqg_put(struct cfq_group *cfqg) { } @@ -1208,11 +1237,33 @@ cfq_update_group_weight(struct cfq_group *cfqg) static void cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) { + struct cfq_group *pos = cfqg; + bool propagate; + + /* add to the service tree */ BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); cfq_update_group_weight(cfqg); __cfq_group_service_tree_add(st, cfqg); st->total_weight += cfqg->weight; + + /* + * Activate @cfqg and propagate activation upwards until we meet an + * already activated node or reach root. + */ + propagate = !pos->nr_active++; + pos->children_weight += pos->leaf_weight; + + while (propagate) { + struct cfq_group *parent = cfqg_flat_parent(pos); + + if (!parent) + break; + + propagate = !parent->nr_active++; + parent->children_weight += pos->weight; + pos = parent; + } } static void @@ -1243,6 +1294,31 @@ cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg) static void cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg) { + struct cfq_group *pos = cfqg; + bool propagate; + + /* + * Undo activation from cfq_group_service_tree_add(). Deactivate + * @cfqg and propagate deactivation upwards. + */ + propagate = !--pos->nr_active; + pos->children_weight -= pos->leaf_weight; + + while (propagate) { + struct cfq_group *parent = cfqg_flat_parent(pos); + + /* @pos has 0 nr_active at this point */ + WARN_ON_ONCE(pos->children_weight); + + if (!parent) + break; + + propagate = !--parent->nr_active; + parent->children_weight -= pos->weight; + pos = parent; + } + + /* remove from the service tree */ st->total_weight -= cfqg->weight; if (!RB_EMPTY_NODE(&cfqg->rb_node)) cfq_rb_erase(&cfqg->rb_node, st); |