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

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
...@@ -333,12 +333,23 @@ The "xxx" is not interpreted by the cgroup code, but will appear in ...@@ -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 To mount a cgroup hierarchy with just the cpuset and numtasks
subsystems, type: 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 To change the set of subsystems bound to a mounted hierarchy, just
remount with different options: 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 Note that changing the set of subsystems is currently only supported
when the hierarchy consists of a single (root) cgroup. Supporting 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 ...@@ -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 tree of the cgroups in the system. For instance, /dev/cgroup
is the cgroup that holds the whole system. 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: If you want to create a new cgroup under /dev/cgroup:
# cd /dev/cgroup # cd /dev/cgroup
# mkdir my_cgroup # mkdir my_cgroup
......
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