Re: [RFC] [PATCH] Cgroup based OOM killer controller

KOSAKI Motohiro
2009-01-27T07:44:54Z

> On Tue, 27 Jan 2009, KOSAKI Motohiro wrote:
>
> > Confused.
> >
> > As far as I know, people want the method of flexible cache treating.
> > but oom seems less flexible than userland notification.
> >
> > Why do you think notification is bad?
> >
>
> There're a couple of proposals that have been discussed recently that
> share some functional behavior.
>
> One is the cgroup oom notifier that allows you to attach a task to wait on
> an oom condition for a collection of tasks. That allows userspace to
> respond to the condition by droping caches, adding nodes to a cpuset,
> elevating memory controller limits, sending a signal, etc. It can also
> defer to the kernel oom killer as a last resort.
>
> The other is /dev/mem_notify that allows you to poll() on a device file
> and be informed of low memory events. This can include the cgroup oom
> notifier behavior when a collection of tasks is completely out of memory,
> but can also warn when such a condition may be imminent. I suggested that
> this be implemented as a client of cgroups so that different handlers can
> be responsible for different aggregates of tasks.
>
> I think the latter is a much more powerful tool and includes all the
> behavior of the former. It preserves the oom killer as a last resort for
> the kernel and defers all preference killing or lowmem responses to
> userspace.

Yup, indeed. :)
honestly, I talked about the same thingk recently "lowmemory android driver not needed?" thread.