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| author | Ben Blum <bblum@andrew.cmu.edu> | 2011-05-26 16:25:20 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-05-26 17:12:34 -0700 |
| commit | 74a1166dfe1135dcc168d35fa5261aa7e087011b (patch) | |
| tree | a7add70f0344e2352b8d0d6beb10aef85c6585f7 /Documentation | |
| parent | f780bdb7c1c73009cb57adcf99ef50027d80bf3c (diff) | |
| download | lwn-74a1166dfe1135dcc168d35fa5261aa7e087011b.tar.gz lwn-74a1166dfe1135dcc168d35fa5261aa7e087011b.zip | |
cgroups: make procs file writable
Make procs file writable to move all threads by tgid at once.
Add functionality that enables users to move all threads in a threadgroup
at once to a cgroup by writing the tgid to the 'cgroup.procs' file. This
current implementation makes use of a per-threadgroup rwsem that's taken
for reading in the fork() path to prevent newly forking threads within the
threadgroup from "escaping" while the move is in progress.
Signed-off-by: Ben Blum <bblum@andrew.cmu.edu>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Reviewed-by: Paul Menage <menage@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/cgroups/cgroups.txt | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt index b3bd3bdbe202..8c4f3466c894 100644 --- a/Documentation/cgroups/cgroups.txt +++ b/Documentation/cgroups/cgroups.txt @@ -236,7 +236,8 @@ containing the following files describing that 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. - This is a read-only file, for now. + Writing a thread group id into this file moves all threads in that + group 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) @@ -430,6 +431,12 @@ You can attach the current shell task by echoing 0: # echo 0 > tasks +You can use the cgroup.procs file instead of the tasks file to move all +threads in a threadgroup at once. Echoing the pid of any task in a +threadgroup to cgroup.procs causes all tasks in that threadgroup to be +be attached to the cgroup. Writing 0 to cgroup.procs moves all tasks +in the writing task's threadgroup. + Note: Since every task is always a member of exactly one cgroup in each mounted hierarchy, to remove a task from its current cgroup you must move it into a new cgroup (possibly the root cgroup) by writing to the |