Update documentation of cgroups tasks and procs files
Document the cgroup.procs file.
Clarify the semantics of the cgroup.procs and tasks files. Although the
current cgroup.procs interface returns a sorted and uniqified list of
pids, potential future performance enhancements could result in those
properties being removed - explicitly document this aspect of the API.
There are no existing users of cgroup.procs, so compatibility isn't an
issue. There are users of the "tasks" file, but none that would appear to
break in the event of the sorted property being broken. The standard
"libcpuset" explicitly sorts the results of reading from the tasks file,
and "libcg" and other users don't appear to care about ordering.
Signed-off-by: Paul Menage <menage@google.com>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Alter the ss->can_attach and ss->attach functions to be able to deal with
a whole threadgroup at a time, for use in cgroup_attach_proc. (This is a
pre-patch to cgroup-procs-writable.patch.)
Currently, new mode of the attach function can only tell the subsystem
about the old cgroup of the threadgroup leader. No subsystem currently
needs that information for each thread that's being moved, but if one were
to be added (for example, one that counts tasks within a group) this bit
would need to be reworked a bit to tell the subsystem the right
information.
[hidave.darkstar@gmail.com: fix build]
Signed-off-by: Ben Blum <bblum@google.com>
Signed-off-by: Paul Menage <menage@google.com>
Acked-by: Li Zefan <lizf@cn.fujitsu.com>
Reviewed-by: Matt Helsley <matthltc@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Dave Young <hidave.darkstar@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
To simplify referring to cgroup hierarchies in mount statements, and to
allow disambiguation in the presence of empty hierarchies and
multiply-bindable subsystems this patch adds support for naming a new
cgroup hierarchy via the "name=" mount option
A pre-existing hierarchy may be specified by either name or by subsystems;
a hierarchy's name cannot be changed by a remount operation.
Example usage:
# To create a hierarchy called "foo" containing the "cpu" subsystem
mount -t cgroup -oname=foo,cpu cgroup /mnt/cgroup1
# To mount the "foo" hierarchy on a second location
mount -t cgroup -oname=foo cgroup /mnt/cgroup2
Signed-off-by: Paul Menage <menage@google.com>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (28 commits)
trivial: Update my email address
trivial: NULL noise: drivers/mtd/tests/mtd_*test.c
trivial: NULL noise: drivers/media/dvb/frontends/drx397xD_fw.h
trivial: Fix misspelling of "Celsius".
trivial: remove unused variable 'path' in alloc_file()
trivial: fix a pdlfush -> pdflush typo in comment
trivial: jbd header comment typo fix for JBD_PARANOID_IOFAIL
trivial: wusb: Storage class should be before const qualifier
trivial: drivers/char/bsr.c: Storage class should be before const qualifier
trivial: h8300: Storage class should be before const qualifier
trivial: fix where cgroup documentation is not correctly referred to
trivial: Give the right path in Documentation example
trivial: MTD: remove EOL from MODULE_DESCRIPTION
trivial: Fix typo in bio_split()'s documentation
trivial: PWM: fix of #endif comment
trivial: fix typos/grammar errors in Kconfig texts
trivial: Fix misspelling of firmware
trivial: cgroups: documentation typo and spelling corrections
trivial: Update contact info for Jochen Hein
trivial: fix typo "resgister" -> "register"
...
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>
In following situation, with memory subsystem,
/groupA use_hierarchy==1
/01 some tasks
/02 some tasks
/03 some tasks
/04 empty
When tasks under 01/02/03 hit limit on /groupA, hierarchical reclaim
is triggered and the kernel walks tree under groupA. In this case,
rmdir /groupA/04 fails with -EBUSY frequently because of temporal
refcnt from the kernel.
In general. cgroup can be rmdir'd if there are no children groups and
no tasks. Frequent fails of rmdir() is not useful to users.
(And the reason for -EBUSY is unknown to users.....in most cases)
This patch tries to modify above behavior, by
- retries if css_refcnt is got by someone.
- add "return value" to pre_destroy() and allows subsystem to
say "we're really busy!"
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Minor typo and spelling corrections fixed whilst reading
to learn about cgroups capabilities.
Signed-off-by: Chris Samuel <chris@csamuel.org>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
The css_set hash table was introduced in 2.6.26, so update the
documentation accordingly.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
These patches introduce new locking/refcount support for cgroups to
reduce the need for subsystems to call cgroup_lock(). This will
ultimately allow the atomicity of cgroup_rmdir() (which was removed
recently) to be restored.
These three patches give:
1/3 - introduce a per-subsystem hierarchy_mutex which a subsystem can
use to prevent changes to its own cgroup tree
2/3 - use hierarchy_mutex in place of calling cgroup_lock() in the
memory controller
3/3 - introduce a css_tryget() function similar to the one recently
proposed by Kamezawa, but avoiding spurious refcount failures in
the event of a race between a css_tryget() and an unsuccessful
cgroup_rmdir()
Future patches will likely involve:
- using hierarchy mutex in place of cgroup_lock() in more subsystems
where appropriate
- restoring the atomicity of cgroup_rmdir() with respect to cgroup_create()
This patch:
Add a hierarchy_mutex to the cgroup_subsys object that protects changes to
the hierarchy observed by that subsystem. It is taken by the cgroup
subsystem (in addition to cgroup_mutex) for the following operations:
- linking a cgroup into that subsystem's cgroup tree
- unlinking a cgroup from that subsystem's cgroup tree
- moving the subsystem to/from a hierarchy (including across the
bind() callback)
Thus if the subsystem holds its own hierarchy_mutex, it can safely
traverse its own hierarchy.
Signed-off-by: Paul Menage <menage@google.com>
Tested-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- remove 'releasable' since it has been moved to the debug subsys.
- update lock requirements of subsys callbacks.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Describe why we need the freezer subsystem and how to use it in a
documentation file. Since the cgroups.txt file is focused on the
subsystem-agnostic portions of cgroups make a directory and move the old
cgroups.txt file at the same time.
Signed-off-by: Matt Helsley <matthltc@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: containers@lists.linux-foundation.org
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
