Re: [RFC PATCH 0/2] Add predictive memory reclamation and compaction

From: Michal Hocko
Date: Wed Aug 28 2019 - 09:15:06 EST

On Wed 28-08-19 18:39:22, Bharath Vedartham wrote:
> > Therefore I would like to shift the discussion towards existing APIs and
> > whether they are suitable for such an advance auto-tuning. I haven't
> > heard any arguments about missing pieces.
> I understand your concern here. Just confirming, by APIs you are
> referring to sysctls, sysfs files and stuff like that right?


> > > If memory exhaustion
> > > occurs, we reclaim some more memory. kswapd stops reclaim when
> > > hwmark is reached. hwmark is usually set to a fairly low percentage of
> > > total memory, in my system for zone Normal hwmark is 13% of total pages.
> > > So there is scope for reclaiming more pages to make sure system does not
> > > suffer from a lack of pages.
> >
> > Yes and we have ways to control those watermarks that your monitoring
> > tool can use to alter the reclaim behavior.
> Just to confirm here, I am aware of one way which is to alter
> min_kfree_bytes values. What other ways are there to alter watermarks
> from user space?

Michal Hocko