Re: OOM detection regressions since 4.7

From: Michal Hocko
Date: Tue Aug 23 2016 - 03:48:59 EST


On Tue 23-08-16 09:40:14, Markus Trippelsdorf wrote:
> On 2016.08.23 at 09:33 +0200, Michal Hocko wrote:
> > On Tue 23-08-16 13:52:45, Joonsoo Kim wrote:
> > [...]
> > > Hello, Michal.
> > >
> > > I agree with partial revert but revert should be a different form.
> > > Below change try to reuse should_compact_retry() version for
> > > !CONFIG_COMPACTION but it turned out that it also causes regression in
> > > Markus report [1].
> >
> > I would argue that CONFIG_COMPACTION=n behaves so arbitrary for high
> > order workloads that calling any change in that behavior a regression
> > is little bit exaggerated. Disabling compaction should have a very
> > strong reason. I haven't heard any so far. I am even wondering whether
> > there is a legitimate reason for that these days.
>
> BTW, the current config description:
>
> CONFIG_COMPACTION:
> Allows the compaction of memory for the allocation of huge pages.
>
> doesn't make it clear to the user that this is an essential feature.

Yes I plan to send a clarification patch.
--
Michal Hocko
SUSE Labs