Re: [RFC] mm: memcg: add priority for soft limit reclaiming

Michal Hocko
2019-09-23T13:28:33Z

On Mon 23-09-19 21:04:59, Hillf Danton wrote:
>
> On Thu, 19 Sep 2019 21:32:31 +0800 Michal Hocko wrote:
> >
> > On Thu 19-09-19 21:13:32, Hillf Danton wrote:
> > >
> > > Currently memory controler is playing increasingly important role in
> > > how memory is used and how pages are reclaimed on memory pressure.
> > >
> > > In daily works memcg is often created for critical tasks and their pre
> > > configured memory usage is supposed to be met even on memory pressure.
> > > Administrator wants to make it configurable that the pages consumed by
> > > memcg-B can be reclaimed by page allocations invoked not by memcg-A but
> > > by memcg-C.
> >
> > I am not really sure I understand the usecase well but this sounds like
> > what memory reclaim protection in v2 is aiming at.
> >

Please describe the usecase.

> A tipoint to the v2 stuff please.

Documentation/admin-guide/cgroup-v2.rst

> > > That configurability is addressed by adding priority for soft limit
> > > reclaiming to make sure that no pages will be reclaimed from memcg of
> > > higer priortiy in favor of memcg of lower priority.
> >
> > cgroup v1 interfaces are generally frozen and mostly aimed at backward
> > compatibility. I am especially concerned about adding a new way to
> > control soft limit which is known to be misdesigned and unfixable to
> > behave reasonably.
> >
> An URL to the drafts/works about the new way in your git tree.

Whut?
--
Michal Hocko
SUSE Labs