diff options
Diffstat (limited to 'Documentation/cgroups/cgroups.txt')
| -rw-r--r-- | Documentation/cgroups/cgroups.txt | 43 |
1 files changed, 38 insertions, 5 deletions
diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt index 6eb1a97e88ce..0b33bfe7dde9 100644 --- a/Documentation/cgroups/cgroups.txt +++ b/Documentation/cgroups/cgroups.txt @@ -227,7 +227,14 @@ as the path relative to the root of the cgroup file system. Each cgroup is represented by a directory in the cgroup file system containing the following files describing that cgroup: - - tasks: list of tasks (by pid) attached to that cgroup + - tasks: list of tasks (by pid) attached to that cgroup. This list + is not guaranteed to be sorted. Writing a thread id into this file + moves the thread into this cgroup. + - cgroup.procs: list of tgids in the cgroup. This list is not + guaranteed to be sorted or free of duplicate tgids, and userspace + should sort/uniquify the list if this property is required. + Writing a tgid into this file moves all threads with that tgid into + this cgroup. - notify_on_release flag: run the release agent on exit? - release_agent: the path to use for release notifications (this file exists in the top cgroup only) @@ -374,7 +381,7 @@ Now you want to do something with this cgroup. In this directory you can find several files: # ls -notify_on_release tasks +cgroup.procs notify_on_release tasks (plus whatever files added by the attached subsystems) Now attach your shell to this cgroup: @@ -408,6 +415,26 @@ You can attach the current shell task by echoing 0: # echo 0 > tasks +2.3 Mounting hierarchies by name +-------------------------------- + +Passing the name=<x> option when mounting a cgroups hierarchy +associates the given name with the hierarchy. This can be used when +mounting a pre-existing hierarchy, in order to refer to it by name +rather than by its set of active subsystems. Each hierarchy is either +nameless, or has a unique name. + +The name should match [\w.-]+ + +When passing a name=<x> option for a new hierarchy, you need to +specify subsystems manually; the legacy behaviour of mounting all +subsystems when none are explicitly specified is not supported when +you give a subsystem a name. + +The name of the subsystem appears as part of the hierarchy description +in /proc/mounts and /proc/<pid>/cgroups. + + 3. Kernel API ============= @@ -501,7 +528,7 @@ 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) + struct task_struct *task, bool threadgroup) (cgroup_mutex held by caller) Called prior to moving a task into a cgroup; if the subsystem @@ -509,14 +536,20 @@ returns an error, this will abort the attach operation. If a NULL task is passed, then a successful result indicates that *any* unspecified task can be moved into the cgroup. Note that this isn't called on a fork. If this method returns 0 (success) then this should -remain valid while the caller holds cgroup_mutex. +remain valid while the caller holds cgroup_mutex. If threadgroup is +true, then a successful result indicates that all threads in the given +thread's threadgroup can be moved together. void attach(struct cgroup_subsys *ss, struct cgroup *cgrp, - struct cgroup *old_cgrp, struct task_struct *task) + struct cgroup *old_cgrp, struct task_struct *task, + bool threadgroup) (cgroup_mutex held by caller) Called after the task has been attached to the cgroup, to allow any post-attachment activity that requires memory allocations or blocking. +If threadgroup is true, the subsystem should take care of all threads +in the specified thread's threadgroup. Currently does not support any +subsystem that might need the old_cgrp for every thread in the group. void fork(struct cgroup_subsy *ss, struct task_struct *task) |