Diffstat (limited to 'Documentation/cgroups/cgroups.txt')
1 files changed, 22 insertions, 4 deletions
diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt
index f4f5ee97d4d..6eb1a97e88c 100644
@@ -333,12 +333,23 @@ The "xxx" is not interpreted by the cgroup code, but will appear in
To mount a cgroup hierarchy with just the cpuset and numtasks
-# mount -t cgroup -o cpuset,numtasks hier1 /dev/cgroup
+# mount -t cgroup -o cpuset,memory hier1 /dev/cgroup
To change the set of subsystems bound to a mounted hierarchy, just
remount with different options:
+# mount -o remount,cpuset,ns hier1 /dev/cgroup
-# mount -o remount,cpuset,ns /dev/cgroup
+Now memory is removed from the hierarchy and ns is added.
+Note this will add ns to the hierarchy but won't remove memory or
+cpuset, because the new options are appended to the old ones:
+# mount -o remount,ns /dev/cgroup
+To Specify a hierarchy's release_agent:
+# mount -t cgroup -o cpuset,release_agent="/sbin/cpuset_release_agent" \
+ xxx /dev/cgroup
+Note that specifying 'release_agent' more than once will return failure.
Note that changing the set of subsystems is currently only supported
when the hierarchy consists of a single (root) cgroup. Supporting
@@ -349,6 +360,11 @@ Then under /dev/cgroup you can find a tree that corresponds to the
tree of the cgroups in the system. For instance, /dev/cgroup
is the cgroup that holds the whole system.
+If you want to change the value of release_agent:
+# echo "/sbin/new_release_agent" > /dev/cgroup/release_agent
+It can also be changed via remount.
If you want to create a new cgroup under /dev/cgroup:
# cd /dev/cgroup
# mkdir my_cgroup
@@ -476,11 +492,13 @@ cgroup->parent is still valid. (Note - can also be called for a
newly-created cgroup if an error occurs after this subsystem's
create() method has been called for the new cgroup).
-void pre_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp);
+int pre_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp);
Called before checking the reference count on each subsystem. This may
be useful for subsystems which have some extra references even if
-there are not tasks in the cgroup.
+there are not tasks in the cgroup. If pre_destroy() returns error code,
+rmdir() will fail with it. From this behavior, pre_destroy() can be
+called multiple times against a cgroup.
int can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
struct task_struct *task)