Commits
Tejun Heo committed 7918ffb5b83
cfq-iosched: implement cfq_group->nr_active and ->children_weight To prepare for blkcg hierarchy support, add cfqg->nr_active and ->children_weight. cfqg->nr_active counts the number of active cfqgs at the cfqg's level and ->children_weight is sum of weights of those cfqgs. The level covers itself (cfqg->leaf_weight) and immediate children. The two values are updated when a cfqg enters and leaves the group service tree. Unless the hierarchy is very deep, the added overhead should be negligible. Currently, the parent is determined using cfqg_flat_parent() which makes the root cfqg the parent of all other cfqgs. This is to make the transition to hierarchy-aware scheduling gradual. Scheduling logic will be converted to use cfqg->children_weight without actually changing the behavior. When everything is ready, blkcg_weight_parent() will be replaced with proper parent function. This patch doesn't introduce any behavior chagne. v2: s/cfqg->level_weight/cfqg->children_weight/ as per Vivek. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Vivek Goyal <vgoyal@redhat.com>