Commit b6719ec1 authored by Li Zefan's avatar Li Zefan Committed by Linus Torvalds
Browse files

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: default avatarLi Zefan <lizf@cn.fujitsu.com>
Reviewd-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 66bdc9cf

Documentation/cgroups/cgroups.txt

+18 −2
Original line number Diff line number Diff line
@@ -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

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