Messages in this thread | | | Date | Thu, 28 Jul 2022 07:26:05 -1000 | From | Tejun Heo <> | Subject | Re: [PATCH 2/2] cgroup: Skip subtree root in cgroup_update_dfl_csses() |
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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@redhat.com> 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
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