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authorRoman Gushchin <guro@fb.com>2017-07-28 19:28:44 +0200
committerTejun Heo <tj@kernel.org>2017-08-02 21:05:20 +0200
commit1a926e0bbab83bae8207d05a533173425e0496d1 (patch)
tree8b0d77250135e254907205b4711e7a7b7174b78e /Documentation/cgroup-v2.txt
parentcgroup: keep track of number of descent cgroups (diff)
downloadlinux-1a926e0bbab83bae8207d05a533173425e0496d1.tar.xz
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cgroup: implement hierarchy limits
Creating cgroup hierearchies of unreasonable size can affect overall system performance. A user might want to limit the size of cgroup hierarchy. This is especially important if a user is delegating some cgroup sub-tree. To address this issue, introduce an ability to control the size of cgroup hierarchy. The cgroup.max.descendants control file allows to set the maximum allowed number of descendant cgroups. The cgroup.max.depth file controls the maximum depth of the cgroup tree. Both are single value r/w files, with "max" default value. The control files exist on each hierarchy level (including root). When a new cgroup is created, we check the total descendants and depth limits on each level, and if none of them are exceeded, a new cgroup is created. Only alive cgroups are counted, removed (dying) cgroups are ignored. Signed-off-by: Roman Gushchin <guro@fb.com> Suggested-by: Tejun Heo <tj@kernel.org> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Zefan Li <lizefan@huawei.com> Cc: Waiman Long <longman@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: kernel-team@fb.com Cc: cgroups@vger.kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org
Diffstat (limited to 'Documentation/cgroup-v2.txt')
-rw-r--r--Documentation/cgroup-v2.txt14
1 files changed, 14 insertions, 0 deletions
diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt
index dec5afdaa36d..46ec3f76211c 100644
--- a/Documentation/cgroup-v2.txt
+++ b/Documentation/cgroup-v2.txt
@@ -854,6 +854,20 @@ All cgroup core files are prefixed with "cgroup."
1 if the cgroup or its descendants contains any live
processes; otherwise, 0.
+ cgroup.max.descendants
+ A read-write single value files. The default is "max".
+
+ Maximum allowed number of descent cgroups.
+ If the actual number of descendants is equal or larger,
+ an attempt to create a new cgroup in the hierarchy will fail.
+
+ cgroup.max.depth
+ A read-write single value files. The default is "max".
+
+ Maximum allowed descent depth below the current cgroup.
+ If the actual descent depth is equal or larger,
+ an attempt to create a new child cgroup will fail.
+
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