mm: hugetlb controller for cgroups v2
In the effort of supporting cgroups v2 into Kubernetes, I stumped on
the lack of the hugetlb controller.
When the controller is enabled, it exposes four new files for each
hugetlb size on non-root cgroups:
- hugetlb.<hugepagesize>.current
- hugetlb.<hugepagesize>.max
- hugetlb.<hugepagesize>.events
- hugetlb.<hugepagesize>.events.local
The differences with the legacy hierarchy are in the file names and
using the value "max" instead of "-1" to disable a limit.
The file .limit_in_bytes is renamed to .max.
The file .usage_in_bytes is renamed to .current.
.failcnt is not provided as a single file anymore, but its value can
be read through the new flat-keyed files .events and .events.local,
through the "max" key.
Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index 0636bcb..3f80146 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -61,6 +61,8 @@
5-6. Device
5-7. RDMA
5-7-1. RDMA Interface Files
+ 5-8. HugeTLB
+ 5.8-1. HugeTLB Interface Files
5-8. Misc
5-8-1. perf_event
5-N. Non-normative information
@@ -2056,6 +2058,33 @@
mlx4_0 hca_handle=1 hca_object=20
ocrdma1 hca_handle=1 hca_object=23
+HugeTLB
+-------
+
+The HugeTLB controller allows to limit the HugeTLB usage per control group and
+enforces the controller limit during page fault.
+
+HugeTLB Interface Files
+~~~~~~~~~~~~~~~~~~~~~~~
+
+ hugetlb.<hugepagesize>.current
+ Show current usage for "hugepagesize" hugetlb. It exists for all
+ the cgroup except root.
+
+ hugetlb.<hugepagesize>.max
+ Set/show the hard limit of "hugepagesize" hugetlb usage.
+ The default value is "max". It exists for all the cgroup except root.
+
+ hugetlb.<hugepagesize>.events
+ A read-only flat-keyed file which exists on non-root cgroups.
+
+ max
+ The number of allocation failure due to HugeTLB limit
+
+ hugetlb.<hugepagesize>.events.local
+ Similar to hugetlb.<hugepagesize>.events but the fields in the file
+ are local to the cgroup i.e. not hierarchical. The file modified event
+ generated on this file reflects only the local events.
Misc
----