Re: Memory reclaim protection and cgroup nesting (desktop use)

[Tejun Heo <tj@kernel.org>]

Hello, Benjamin.

On Thu, Mar 05, 2020 at 04:27:19PM +0100, Benjamin Berg wrote:
> > Changing memory limits dynamically can lead to pretty abrupt system
> > behaviors depending on how big the swing is but memory.low and io/cpu
> > weights should behave fine.
> 
> Right, we'll need some daemon to handle this, so we could even smooth
> out any change over a period of time. But it seems like that will not
> be needed. I don't expect we'll want to change anything beyond
> memory.low and io/cpu weights.

Yeah, you don't need to baby memory.low and io/cpu weights at all.

> > Sounds great. In our experience, what would help quite a lot is using
> > per-application cgroups more (e.g. containing each application as user
> > services) so that one misbehaving command can't overwhelm the session
> > and eventually when oomd has to kick in, it can identify and kill only
> > the culprit application rather than the whole session.
> 
> We are already trying to do this in GNOME. :)

Awesome.

> Right now GNOME is only moving processes into cgroups after launching
> them though (i.e. transient systemd scopes).

Even just that would be plenty helpful.

> But, the goal here is to improve it further and launch all
> applications directly using systemd (i.e. as systemd services). systemd
> itself is going to define some standards to facilitate everything. And
> we'll probably also need to update some XDG standards.
> 
> So, there are some plans already, but many details have not been solved
> yet. But at least KDE and GNOME people are looking into integrating
> well with systemd.

Sounds great. Please let us know if there's anything we can help with.

Thanks.

-- 
tejun