Re: [PATCH v10 5/9] cpuset: Make sure that domain roots work properly with CPU hotplug
From: Peter Zijlstra <peterz@infradead.org>
Date: 2018-06-20 14:16:03
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On Mon, Jun 18, 2018 at 12:14:04PM +0800, Waiman Long wrote:
quoted hunk ↗ jump to hunk
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.