Re: [PATCH v10 5/9] cpuset: Make sure that domain roots work properly with CPU hotplug

Waiman Long
2018-06-21T03:09:35Z

On 06/20/2018 10:15 PM, Peter Zijlstra wrote:
> On Mon, Jun 18, 2018 at 12:14:04PM +0800, Waiman Long wrote:
>> diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
>> index 5ee5e77..6ef3516 100644
>> --- a/Documentation/admin-guide/cgroup-v2.rst
>> +++ b/Documentation/admin-guide/cgroup-v2.rst
>> @@ -1626,6 +1626,13 @@ Cpuset Interface Files
>> 2) No CPU that has been distributed to child scheduling domain
>> roots is deleted.
>>
>> + When all the CPUs allocated to a scheduling domain are offlined,
>> + that scheduling domain will be temporaily gone and all the
>> + tasks in that scheduling domain will migrate to another one that
>> + belongs to the parent of the scheduling domain root. When any
>> + of those offlined CPUs is onlined again, a new scheduling domain
>> + will be re-created and the tasks will be migrated back.
>> +
> You should mention that this is a destructive operation. If any of the
> tasks had an affinity smaller than the original cgroup, that will be
> gone.

Thanks for the information. Will update the documentation to mention that.

Cheers,
Longman