cgroups: support named cgroups hierarchies
To simplify referring to cgroup hierarchies in mount statements, and to
allow disambiguation in the presence of empty hierarchies and
multiply-bindable subsystems this patch adds support for naming a new
cgroup hierarchy via the "name=" mount option
A pre-existing hierarchy may be specified by either name or by subsystems;
a hierarchy's name cannot be changed by a remount operation.
Example usage:
# To create a hierarchy called "foo" containing the "cpu" subsystem
mount -t cgroup -oname=foo,cpu cgroup /mnt/cgroup1
# To mount the "foo" hierarchy on a second location
mount -t cgroup -oname=foo cgroup /mnt/cgroup2
Signed-off-by: Paul Menage <menage@google.com>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt
index 6eb1a97..4bccfc1 100644
--- a/Documentation/cgroups/cgroups.txt
+++ b/Documentation/cgroups/cgroups.txt
@@ -408,6 +408,26 @@
# echo 0 > tasks
+2.3 Mounting hierarchies by name
+--------------------------------
+
+Passing the name=<x> option when mounting a cgroups hierarchy
+associates the given name with the hierarchy. This can be used when
+mounting a pre-existing hierarchy, in order to refer to it by name
+rather than by its set of active subsystems. Each hierarchy is either
+nameless, or has a unique name.
+
+The name should match [\w.-]+
+
+When passing a name=<x> option for a new hierarchy, you need to
+specify subsystems manually; the legacy behaviour of mounting all
+subsystems when none are explicitly specified is not supported when
+you give a subsystem a name.
+
+The name of the subsystem appears as part of the hierarchy description
+in /proc/mounts and /proc/<pid>/cgroups.
+
+
3. Kernel API
=============