Merge branches 'x86-build-for-linus', 'x86-cleanups-for-linus' and 'x86-debug-for...

[firefly-linux-kernel-4.4.55.git] / Documentation / cgroups / unified-hierarchy.txt

diff --git a/Documentation/cgroups/unified-hierarchy.txt b/Documentation/cgroups/unified-hierarchy.txt
index 324b182e6000823eda8fa22924173ee957c32647..4f4563277864f4ce3a2bc17c76c61f7a4002e3bc 100644 (file)
--- a/Documentation/cgroups/unified-hierarchy.txt
+++ b/Documentation/cgroups/unified-hierarchy.txt
@@ -94,12 +94,35 @@ 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 at any time.  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
+controller states are destroyed asynchronously and controllers may
+have lingering references, a controller may not show up immediately on
+the unified hierarchy after the final umount of the previous
+hierarchy.  Similarly, a controller should be fully disabled to be
+moved out of the unified hierarchy and it may take some time for the
+disabled controller to become available for other hierarchies;
+furthermore, due to dependencies among controllers, other controllers
+may need to be disabled too.
+
+While useful for development and manual configurations, dynamically
+moving controllers between the unified and other hierarchies is
+strongly discouraged for production use.  It is recommended to decide
+the hierarchies and controller associations before starting using the
+controllers.
 
 
 2-2. cgroup.subtree_control