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| author | Roman Gushchin <guro@fb.com> | 2017-08-02 17:55:31 +0100 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2017-08-02 12:05:20 -0700 |
| commit | ec39225cca42c05ac36853d11d28f877fde5c42e (patch) | |
| tree | 7291a1c4befe3cd890a28802fce26c0f7e6e81f5 /Documentation/cgroup-v2.txt | |
| parent | 1a926e0bbab83bae8207d05a533173425e0496d1 (diff) | |
| download | op-kernel-dev-ec39225cca42c05ac36853d11d28f877fde5c42e.zip op-kernel-dev-ec39225cca42c05ac36853d11d28f877fde5c42e.tar.gz | |
cgroup: add cgroup.stat interface with basic hierarchy stats
A cgroup can consume resources even after being deleted by a user.
For example, writing back dirty pages should be accounted and
limited, despite the corresponding cgroup might contain no processes
and being deleted by a user.
In the current implementation a cgroup can remain in such "dying" state
for an undefined amount of time. For instance, if a memory cgroup
contains a pge, mlocked by a process belonging to an other cgroup.
Although the lifecycle of a dying cgroup is out of user's control,
it's important to have some insight of what's going on under the hood.
In particular, it's handy to have a counter which will allow
to detect css leaks.
To solve this problem, add a cgroup.stat interface to
the base cgroup control files with the following metrics:
nr_descendants total number of visible descendant cgroups
nr_dying_descendants total number of dying descendant cgroups
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.txt | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt index 46ec3f7..dc44785 100644 --- a/Documentation/cgroup-v2.txt +++ b/Documentation/cgroup-v2.txt @@ -868,6 +868,24 @@ All cgroup core files are prefixed with "cgroup." If the actual descent depth is equal or larger, an attempt to create a new child cgroup will fail. + cgroup.stat + A read-only flat-keyed file with the following entries: + + nr_descendants + Total number of visible descendant cgroups. + + nr_dying_descendants + Total number of dying descendant cgroups. A cgroup becomes + dying after being deleted by a user. The cgroup will remain + in dying state for some time undefined time (which can depend + on system load) before being completely destroyed. + + A process can't enter a dying cgroup under any circumstances, + a dying cgroup can't revive. + + A dying cgroup can consume system resources not exceeding + limits, which were active at the moment of cgroup deletion. + Controllers =========== |
