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memcg: oom kill disable and oom status

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This adds a feature to disable oom-killer for memcg, if disabled, of
course, tasks under memcg will stop.

But now, we have oom-notifier for memcg.  And the world around memcg is
not under out-of-memory.  memcg's out-of-memory just shows memcg hits
limit.  Then, administrator or management daemon can recover the situation
by

	- kill some process
	- enlarge limit, add more swap.
	- migrate some tasks
	- remove file cache on tmps (difficult ?)

Unlike oom-killer, you can take enough information before killing tasks.
(by gcore, or, ps etc.)

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
KAMEZAWA Hiroyuki
2010-05-26 14:42:37 -07:00
committed by Linus Torvalds
parent 9490ff2756
commit 3c11ecf448
2 changed files with 117 additions and 19 deletions
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23
Documentation/cgroups/memory.txt
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@ -493,6 +493,8 @@ It's applicable for root and non-root cgroup.
10. OOM Control
memory.oom_control file is for OOM notification and other controls.
Memory controler implements oom notifier using cgroup notification
API (See cgroups.txt). It allows to register multiple oom notification
delivery and gets notification when oom happens.
@ -505,6 +507,27 @@ To register a notifier, application need:
Application will be notifier through eventfd when oom happens.
OOM notification doesn't work for root cgroup.
You can disable oom-killer by writing "1" to memory.oom_control file.
As.
#echo 1 > memory.oom_control
This operation is only allowed to the top cgroup of subhierarchy.
If oom-killer is disabled, tasks under cgroup will hang/sleep
in memcg's oom-waitq when they request accountable memory.
For running them, you have to relax the memcg's oom sitaution by
* enlarge limit or reduce usage.
To reduce usage,
* kill some tasks.
* move some tasks to other group with account migration.
* remove some files (on tmpfs?)
Then, stopped tasks will work again.
At reading, current status of OOM is shown.
oom_kill_disable 0 or 1 (if 1, oom-killer is disabled)
under_oom 0 or 1 (if 1, the memcg is under OOM,tasks may
be stopped.)
11. TODO