From: Michal Hocko <mhocko@kernel.org>
To: Sultan Alsawaf <sultan@kerneltoast.com>
Cc: "Suren Baghdasaryan" <surenb@google.com>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Arve Hjønnevåg" <arve@android.com>,
"Todd Kjos" <tkjos@android.com>,
"Martijn Coenen" <maco@android.com>,
"Joel Fernandes" <joel@joelfernandes.org>,
"Christian Brauner" <christian@brauner.io>,
"Ingo Molnar" <mingo@redhat.com>,
"Peter Zijlstra" <peterz@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
devel@driverdev.osuosl.org, linux-mm <linux-mm@kvack.org>,
"Tim Murray" <timmurray@google.com>
Subject: Re: [RFC] simple_lmk: Introduce Simple Low Memory Killer for Android
Date: Tue, 12 Mar 2019 17:48:57 +0100 [thread overview]
Message-ID: <20190312164857.GE5721@dhcp22.suse.cz> (raw)
In-Reply-To: <20190312163741.GA2762@sultan-box.localdomain>
On Tue 12-03-19 09:37:41, Sultan Alsawaf wrote:
> On Tue, Mar 12, 2019 at 09:05:32AM +0100, Michal Hocko wrote:
> > The only way to control the OOM behavior pro-actively is to throttle
> > allocation speed. We have memcg high limit for that purpose. Along with
> > PSI, I can imagine a reasonably working user space early oom
> > notifications and reasonable acting upon that.
>
> The issue with pro-active memory management that prompted me to create this was
> poor memory utilization. All of the alternative means of reclaiming pages in the
> page allocator's slow path turn out to be very useful for maximizing memory
> utilization, which is something that we would have to forgo by relying on a
> purely pro-active solution. I have not had a chance to look at PSI yet, but
> unless a PSI-enabled solution allows allocations to reach the same point as when
> the OOM killer is invoked (which is contradictory to what it sets out to do),
> then it cannot take advantage of all of the alternative memory-reclaim means
> employed in the slowpath, and will result in killing a process before it is
> _really_ necessary.
If you really want to reach the real OOM situation then you can very
well rely on the in-kernel OOM killer. The only reason you want a
customized oom killer is the tasks clasification. And that is a
different story. User space hints on the victim selection has been a
topic for quite while. It never get to any conclusion as interested
parties have always lost an interest because it got hairy quickly.
> > If you design is relies on the speed of killing then it is fundamentally
> > flawed AFAICT. You cannot assume anything about how quickly a task dies.
> > It might be blocked in an uninterruptible sleep or performin an
> > operation which takes some time. Sure, oom_reaper might help here but
> > still.
>
> In theory we could instantly zap any process that is not trapped in the kernel
> at the time that the OOM killer is invoked without any consequences though, no?
No, this is not so simple. Have a look at the oom_reaper and hops it has
to go through.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2019-03-12 16:49 UTC|newest]
Thread overview: 113+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-10 20:34 [RFC] simple_lmk: Introduce Simple Low Memory Killer for Android Sultan Alsawaf
2019-03-10 21:03 ` Greg Kroah-Hartman
2019-03-10 21:26 ` Sultan Alsawaf
2019-03-11 16:32 ` Joel Fernandes
2019-03-11 16:37 ` Joel Fernandes
2019-03-11 17:43 ` Michal Hocko
2019-03-11 17:58 ` Sultan Alsawaf
2019-03-11 20:10 ` Suren Baghdasaryan
2019-03-11 20:46 ` Sultan Alsawaf
2019-03-11 21:11 ` Joel Fernandes
2019-03-11 21:46 ` Sultan Alsawaf
2019-03-11 22:15 ` Suren Baghdasaryan
2019-03-11 22:36 ` Sultan Alsawaf
2019-03-12 8:05 ` Michal Hocko
2019-03-12 14:36 ` Suren Baghdasaryan
2019-03-12 15:25 ` Matthew Wilcox
2019-03-12 15:33 ` Michal Hocko
2019-03-12 15:39 ` Michal Hocko
2019-03-12 16:37 ` Sultan Alsawaf
2019-03-12 16:48 ` Michal Hocko [this message]
2019-03-12 16:58 ` Michal Hocko
2019-03-12 17:15 ` Suren Baghdasaryan
2019-03-12 17:17 ` Tim Murray
2019-03-12 17:45 ` Sultan Alsawaf
2019-03-12 18:43 ` Tim Murray
2019-03-12 18:50 ` Christian Brauner
2019-03-14 17:47 ` Joel Fernandes
2019-03-14 20:49 ` Sultan Alsawaf
2019-03-15 2:54 ` Joel Fernandes
2019-03-15 3:43 ` Sultan Alsawaf
2019-03-15 3:16 ` Steven Rostedt
2019-03-15 3:45 ` Sultan Alsawaf
2019-03-15 4:36 ` Daniel Colascione
2019-03-15 13:36 ` Joel Fernandes
2019-03-15 15:56 ` Suren Baghdasaryan
2019-03-15 16:12 ` Daniel Colascione
2019-03-15 16:43 ` Steven Rostedt
2019-03-15 17:17 ` Daniel Colascione
2019-03-15 18:03 ` Christian Brauner
2019-03-15 18:13 ` Joel Fernandes
2019-03-15 18:24 ` Christian Brauner
2019-03-15 18:49 ` Joel Fernandes
2019-03-16 17:31 ` Suren Baghdasaryan
2019-03-16 18:00 ` Daniel Colascione
2019-03-16 18:57 ` Christian Brauner
2019-03-16 19:37 ` Suren Baghdasaryan
2019-03-17 1:53 ` Joel Fernandes
2019-03-17 11:42 ` Christian Brauner
2019-03-17 15:40 ` Daniel Colascione
2019-03-18 0:29 ` Christian Brauner
2019-03-18 23:50 ` Joel Fernandes
2019-03-19 22:14 ` Christian Brauner
2019-03-19 22:26 ` Joel Fernandes
2019-03-19 22:48 ` Daniel Colascione
2019-03-19 23:10 ` Christian Brauner
2019-03-20 1:52 ` Joel Fernandes
2019-03-20 2:42 ` pidfd design Daniel Colascione
2019-03-20 3:59 ` Christian Brauner
2019-03-20 7:02 ` Daniel Colascione
2019-03-20 11:33 ` Joel Fernandes
2019-03-20 18:26 ` Christian Brauner
2019-03-20 18:38 ` Daniel Colascione
2019-03-20 18:51 ` Christian Brauner
2019-03-20 18:58 ` Andy Lutomirski
2019-03-20 19:14 ` Christian Brauner
2019-03-20 19:40 ` Daniel Colascione
2019-03-21 17:02 ` Andy Lutomirski
2019-03-25 20:13 ` Jann Horn
2019-03-25 20:23 ` Daniel Colascione
2019-03-25 23:42 ` Andy Lutomirski
2019-03-25 23:45 ` Christian Brauner
2019-03-26 0:00 ` Andy Lutomirski
2019-03-26 0:12 ` Christian Brauner
2019-03-26 0:24 ` Andy Lutomirski
2019-03-28 9:21 ` Christian Brauner
2019-03-20 19:19 ` Joel Fernandes
2019-03-20 19:29 ` Daniel Colascione
2019-03-24 14:44 ` Serge E. Hallyn
2019-03-24 18:48 ` Joel Fernandes
2019-03-20 19:11 ` Joel Fernandes
2019-05-07 2:16 ` [RFC] simple_lmk: Introduce Simple Low Memory Killer for Android Sultan Alsawaf
2019-05-07 7:04 ` Greg Kroah-Hartman
2019-05-07 7:27 ` Sultan Alsawaf
2019-05-07 7:43 ` Greg Kroah-Hartman
2019-05-07 8:12 ` Sultan Alsawaf
2019-05-07 10:58 ` Christian Brauner
2019-05-07 16:28 ` Suren Baghdasaryan
2019-05-07 16:38 ` Christian Brauner
2019-05-07 16:53 ` Sultan Alsawaf
2019-05-07 20:01 ` Suren Baghdasaryan
2019-05-07 18:46 ` Joel Fernandes
2019-05-07 17:17 ` Sultan Alsawaf
2019-05-07 17:29 ` Greg Kroah-Hartman
2019-05-07 11:09 ` Greg Kroah-Hartman
2019-05-07 12:26 ` Michal Hocko
2019-05-07 15:31 ` Oleg Nesterov
2019-05-07 16:35 ` Sultan Alsawaf
2019-05-09 15:56 ` Oleg Nesterov
2019-05-09 18:33 ` Sultan Alsawaf
2019-05-10 15:10 ` Oleg Nesterov
2019-05-13 16:45 ` Sultan Alsawaf
2019-05-14 16:44 ` Steven Rostedt
2019-05-14 17:31 ` Sultan Alsawaf
2019-05-15 14:58 ` Oleg Nesterov
2019-05-15 17:27 ` Sultan Alsawaf
2019-05-15 18:32 ` Steven Rostedt
2019-05-15 18:52 ` Sultan Alsawaf
2019-05-15 20:09 ` Steven Rostedt
2019-05-16 13:54 ` Oleg Nesterov
2019-03-17 16:35 ` Serge E. Hallyn
2019-03-17 17:11 ` Daniel Colascione
2019-03-17 17:16 ` Serge E. Hallyn
2019-03-17 22:02 ` Suren Baghdasaryan
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