summaryrefslogtreecommitdiff
path: root/Documentation/cgroups
diff options
context:
space:
mode:
authorTejun Heo <tj@kernel.org>2014-07-15 11:05:10 -0400
committerTejun Heo <tj@kernel.org>2014-07-15 11:05:10 -0400
commita8ddc8215e1a4cd9dc5d6210811cfc381a489ec2 (patch)
tree647056238f18f982969e1aad6d2f564e99d99d65 /Documentation/cgroups
parent2cf669a58dc08fa065a8bd0dca866c0e6cb358cc (diff)
cgroup: distinguish the default and legacy hierarchies when handling cftypes
Until now, cftype arrays carried files for both the default and legacy hierarchies and the files which needed to be used on only one of them were flagged with either CFTYPE_ONLY_ON_DFL or CFTYPE_INSANE. This gets confusing very quickly and we may end up exposing interface files to the default hierarchy without thinking it through. This patch makes cgroup core provide separate sets of interfaces for cftype handling so that the cftypes for the default and legacy hierarchies are clearly distinguished. The previous two patches renamed the existing ones so that they clearly indicate that they're for the legacy hierarchies. This patch adds the interface for the default hierarchy and apply them selectively depending on the hierarchy type. * cftypes added through cgroup_subsys->dfl_cftypes and cgroup_add_dfl_cftypes() only show up on the default hierarchy. * cftypes added through cgroup_subsys->legacy_cftypes and cgroup_add_legacy_cftypes() only show up on the legacy hierarchies. * cgroup_subsys->dfl_cftypes and ->legacy_cftypes can point to the same array for the cases where the interface files are identical on both types of hierarchies. * This makes all the existing subsystem interface files legacy-only by default and all subsystems will have no interface file created when enabled on the default hierarchy. Each subsystem should explicitly review and compose the interface for the default hierarchy. * A boot param "cgroup__DEVEL__legacy_files_on_dfl" is added which makes subsystems which haven't decided the interface files for the default hierarchy to present the legacy files on the default hierarchy so that its behavior on the default hierarchy can be tested. As the awkward name suggests, this is for development only. * memcg's CFTYPE_INSANE on "use_hierarchy" is noop now as the whole array isn't used on the default hierarchy. The flag is removed. v2: Updated documentation for cgroup__DEVEL__legacy_files_on_dfl. v3: Clear CFTYPE_ONLY_ON_DFL and CFTYPE_INSANE when cfts are removed as suggested by Li. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Aristeu Rozanski <aris@redhat.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Diffstat (limited to 'Documentation/cgroups')
-rw-r--r--Documentation/cgroups/unified-hierarchy.txt18
1 files changed, 12 insertions, 6 deletions
diff --git a/Documentation/cgroups/unified-hierarchy.txt b/Documentation/cgroups/unified-hierarchy.txt
index a7a2205539a7..4f4563277864 100644
--- a/Documentation/cgroups/unified-hierarchy.txt
+++ b/Documentation/cgroups/unified-hierarchy.txt
@@ -94,12 +94,18 @@ change soon.
mount -t cgroup -o __DEVEL__sane_behavior cgroup $MOUNT_POINT
-All controllers which are not bound to other hierarchies are
-automatically bound to unified hierarchy and show up at the root of
-it. Controllers which are enabled only in the root of unified
-hierarchy can be bound to other hierarchies. This allows mixing
-unified hierarchy with the traditional multiple hierarchies in a fully
-backward compatible way.
+All controllers which support the unified hierarchy and are not bound
+to other hierarchies are automatically bound to unified hierarchy and
+show up at the root of it. Controllers which are enabled only in the
+root of unified hierarchy can be bound to other hierarchies. This
+allows mixing unified hierarchy with the traditional multiple
+hierarchies in a fully backward compatible way.
+
+For development purposes, the following boot parameter makes all
+controllers to appear on the unified hierarchy whether supported or
+not.
+
+ cgroup__DEVEL__legacy_files_on_dfl
A controller can be moved across hierarchies only after the controller
is no longer referenced in its current hierarchy. Because per-cgroup