Re: [PATCH] mm,oom: Bring OOM notifier callbacks to outside of OOM killer.

From: Michal Hocko
Date: Thu Jun 28 2018 - 15:06:41 EST


On Wed 27-06-18 07:31:25, Paul E. McKenney wrote:
> On Wed, Jun 27, 2018 at 09:22:07AM +0200, Michal Hocko wrote:
> > On Tue 26-06-18 10:03:45, Paul E. McKenney wrote:
> > [...]
> > > 3. Something else?
> >
> > How hard it would be to use a different API than oom notifiers? E.g. a
> > shrinker which just kicks all the pending callbacks if the reclaim
> > priority reaches low values (e.g. 0)?
>
> Beats me. What is a shrinker? ;-)

This is a generich mechanism to reclaim memory that is not on standard
LRU lists. Lwn.net surely has some nice coverage (e.g.
https://lwn.net/Articles/548092/).

> More seriously, could you please point me at an exemplary shrinker
> use case so I can see what is involved?

Well, I am not really sure what is the objective of the oom notifier to
point you to the right direction. IIUC you just want to kick callbacks
to be handled sooner under a heavy memory pressure, right? How is that
achieved? Kick a worker?
--
Michal Hocko
SUSE Labs