From: Roman Gushchin <guro@fb.com>
To: David Rientjes <rientjes@google.com>
Cc: linux-mm@kvack.org, akpm@linux-foundation.org, mhocko@kernel.org,
hannes@cmpxchg.org, tj@kernel.org, gthelen@google.com
Subject: Re: cgroup-aware OOM killer, how to move forward
Date: Fri, 13 Jul 2018 15:16:07 -0700 [thread overview]
Message-ID: <20180713221602.GA15005@castle.DHCP.thefacebook.com> (raw)
In-Reply-To: <alpine.DEB.2.21.1807131423230.194789@chino.kir.corp.google.com>
On Fri, Jul 13, 2018 at 02:34:49PM -0700, David Rientjes wrote:
> On Wed, 11 Jul 2018, Roman Gushchin wrote:
>
> > I was thinking on how to move forward with the cgroup-aware OOM killer.
> > It looks to me, that we all agree on the "cleanup" part of the patchset:
> > it's a nice feature to be able to kill all tasks in the cgroup
> > to guarantee the consistent state of the workload.
> > All our disagreements are related to the victim selection algorithm.
> >
> > So, I wonder, if the right thing to do is to split the problem.
> > We can agree on the "cleanup" part, which is useful by itself,
> > merge it upstream, and then return to the victim selection
> > algorithm.
> >
> > So, here is my proposal:
> > let's introduce the memory.group_oom knob with the following semantics:
> > if the knob is set, the OOM killer can kill either none, either all
> > tasks in the cgroup*.
> > It can perfectly work with the current OOM killer (as a "cleanup" option),
> > and allows _any_ further approach on the OOM victim selection.
> > It also doesn't require any mount/boot/tree-wide options.
> >
> > How does it sound?
> >
>
> No objection, of course, this was always the mechanism vs policy
> separation that I was referring to. Having the ability to kill all
> processes attached to the cgroup when one of its processes is selected is
> useful, and we have our own patches that do just that, with the exception
> that it's triggerable by the user.
Perfect! I'll prepare the patchset.
>
> One of the things that I really like about cgroup v2, though, is what
> appears to be an implicit, but rather apparent, goal to minimize the
> number of files for each controller. It's very clean. So I'd suggest
> that we consider memory.group_oom, or however it is named, to allow for
> future development.
>
> For example, rather than simply being binary, we'd probably want the
> ability to kill all eligible processes attached directly to the victim's
> mem cgroup *or* all processes attached to its subtree as well.
>
> I'd suggest it be implemented to accept a string, "default"/"process",
> "local" or "tree"/"hierarchy", or better names, to define the group oom
> mechanism for the mem cgroup that is oom when one of its processes is
> selected as a victim.
I would prefer to keep it boolean to match the simplicity of cgroup v2 API.
In v2 hierarchy processes can't be attached to non-leaf cgroups,
so I don't see the place for the 3rd meaning.
>
> > * More precisely: if the OOM killer kills a task,
> > it will traverse the cgroup tree up to the OOM domain (OOMing memcg or root),
> > looking for the highest-level cgroup with group_oom set. Then it will
> > kill all tasks in such cgroup, if it does exist.
> >
>
> All such processes that are not oom disabled, yes.
>
Yep, of course.
Thanks!
next prev parent reply other threads:[~2018-07-13 22:16 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-11 22:40 cgroup-aware OOM killer, how to move forward Roman Gushchin
2018-07-12 12:07 ` Michal Hocko
2018-07-12 15:55 ` Roman Gushchin
2018-07-13 21:34 ` David Rientjes
2018-07-13 22:16 ` Roman Gushchin [this message]
2018-07-13 22:39 ` David Rientjes
2018-07-13 23:05 ` Roman Gushchin
2018-07-13 23:11 ` David Rientjes
2018-07-13 23:16 ` Roman Gushchin
2018-07-17 4:19 ` David Rientjes
2018-07-17 12:41 ` Michal Hocko
2018-07-17 17:38 ` Roman Gushchin
2018-07-17 19:49 ` Michal Hocko
2018-07-17 20:06 ` Roman Gushchin
2018-07-17 20:41 ` David Rientjes
2018-07-17 20:52 ` Roman Gushchin
2018-07-20 8:30 ` David Rientjes
2018-07-20 11:21 ` Tejun Heo
2018-07-20 16:13 ` Roman Gushchin
2018-07-20 20:28 ` David Rientjes
2018-07-20 20:47 ` Roman Gushchin
2018-07-23 23:06 ` David Rientjes
2018-07-23 14:12 ` Michal Hocko
2018-07-18 8:19 ` Michal Hocko
2018-07-18 8:12 ` Michal Hocko
2018-07-18 15:28 ` Roman Gushchin
2018-07-19 7:38 ` Michal Hocko
2018-07-19 17:05 ` Roman Gushchin
2018-07-20 8:32 ` David Rientjes
2018-07-23 14:17 ` Michal Hocko
2018-07-23 15:09 ` Tejun Heo
2018-07-24 7:32 ` Michal Hocko
2018-07-24 13:08 ` Tejun Heo
2018-07-24 13:26 ` Michal Hocko
2018-07-24 13:31 ` Tejun Heo
2018-07-24 13:50 ` Michal Hocko
2018-07-24 13:55 ` Tejun Heo
2018-07-24 14:25 ` Michal Hocko
2018-07-24 14:28 ` Tejun Heo
2018-07-24 14:35 ` Tejun Heo
2018-07-24 14:43 ` Michal Hocko
2018-07-24 14:49 ` Tejun Heo
2018-07-24 15:52 ` Roman Gushchin
2018-07-25 12:00 ` Michal Hocko
2018-07-25 11:58 ` Michal Hocko
2018-07-30 8:03 ` Michal Hocko
2018-07-30 14:04 ` Tejun Heo
2018-07-30 15:29 ` Roman Gushchin
2018-07-24 11:59 ` Tetsuo Handa
2018-07-25 0:10 ` Roman Gushchin
2018-07-25 12:23 ` Tetsuo Handa
2018-07-25 13:01 ` Michal Hocko
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