[PATCH 7/7] cgroups: Update documentation for bindable subsystems
lizf at cn.fujitsu.com
Fri Oct 22 01:12:25 PDT 2010
Provide a usage example, and update the bind() callback API.
Signed-off-by: Li Zefan <lizf at cn.fujitsu.com>
Documentation/cgroups/cgroups.txt | 26 +++++++++++++++++---------
1 files changed, 17 insertions(+), 9 deletions(-)
diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt
index 190018b..5b5382a 100644
@@ -363,17 +363,23 @@ 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
+For some subsystems you can bind them to a mounted hierarchy or
+remove them from it, even if there're sub-cgroups in it:
+# mount -t cgroup -o freezer hier1 /dev/cgroup
+# echo $$ > /dev/cgroup/my_cgroup
+# mount -o freezer,cpuset hier1 /dev/cgroup
+# mount -o freezer,cpuacct hier1 /dev/cgroup
+# mount -o cpuacct hier1 /dev/cgroup
+Note cpuacct should be sit in the default hierarchy before remount.
To Specify a hierarchy's release_agent:
# mount -t cgroup -o cpuset,release_agent="/sbin/cpuset_release_agent" \
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
-the ability to arbitrarily bind/unbind subsystems from an existing
-cgroup hierarchy is intended to be implemented in the future.
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.
@@ -623,13 +629,15 @@ initialization which might be required before a task could attach. For
example in cpusets, no task may attach before 'cpus' and 'mems' are set
-void bind(struct cgroup_subsys *ss, struct cgroup *root)
+void bind(struct cgroup_subsys *ss, struct cgroup *cgrp, bool unbind)
(cgroup_mutex and ss->hierarchy_mutex held by caller)
Called when a cgroup subsystem is rebound to a different hierarchy
-and root cgroup. Currently this will only involve movement between
-the default hierarchy (which never has sub-cgroups) and a hierarchy
-that is being created/destroyed (and hence has no sub-cgroups).
+and root cgroup. For some subsystems this will only involve movement
+between the default hierarchy (which never has sub-cgroups) and a
+hierarchy that is being created/destroyed (and hence has no sub-cgroups).
+For some other subsystems this can involve movement between the default
+hierarchy and a mounted hierarchy which may have sub-cgroups in it.
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