Re: [PATCH 2/2] cgroup: Skip subtree root in cgroup_update_dfl_csses()

[Waiman Long <longman@redhat.com>]

On 7/28/22 10:44, 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.
>
It is more an optimization patch trying to not waste cpu time doing 
unnecessary work.
>> ---
>>   kernel/cgroup/cgroup.c | 9 +++++++++
>>   1 file changed, 9 insertions(+)
> Feel free to have
> Reviewed-by: Michal Koutný <mkoutny@suse.com>
>
Thanks for the review.

Cheers,
Longman