cgroups: more documentation for remount and release_agent

This won't remove cpuacct from the mounted hierachy:
 # mount -t cgroup -o cpu,cpuacct xxx /mnt
 # mount -o remount,cpu /mnt

Because for this usage mount(8) will append the new options to the original
options.

And this will get you right:
 # mount [-t cgroup] -o remount,cpu xxx /mnt

Also document how to specify or change release_agent.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Reviewd-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Li Zefan 2009-04-02 16:57:28 -07:00 committed by Linus Torvalds
parent 66bdc9cfc7
commit b6719ec1ad

View File

@ -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
subsystems, type:
# 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