On Thu, Jul 28, 2022 at 04:44:26PM +0200, Michal Koutný wrote: > On Wed, Jul 27, 2022 at 08:58:15PM -0400, Waiman Long <longman@xxxxxxxxxx> wrote: > > The cgroup_update_dfl_csses() function updates css associations when a > > cgroup's subtree_control file is modified. Any changes made to a cgroup's > > subtree_control file, however, will only affect its descendants but not > > the cgroup itself. > > I find this correct. > > > So there is no point in migrating csses associated with that cgroup. > > We can skip them instead. > > Alone it's not such a big win but it componds with the recent Tejun's > threadgroup_rwsem elision. The chance is that if you're writing to a cgroup's subtree_control, that cgroup is gonna be empty. The only case I can think of that this would make a difference is w/ threaded cgroups, but it does make sense. Thanks. -- tejun
