Re: [patch] mm: oom_kill: revert 3% system memory bonus for privileged tasks

David Rientjes
2014-01-22T04:53:12Z

On Thu, 16 Jan 2014, Johannes Weiner wrote:

> > Unfortunately, I think this could potentially be too much of a bonus. On
> > your same 32GB machine, if a root process is using 18GB and a user process
> > is using 14GB, the user process ends up getting selected while the current
> > discount of 3% still selects the root process.
> >
> > I do like the idea of scaling this bonus depending on points, however. I
> > think it would be better if we could scale the discount but also limit it
> > to some sane value.
>
> I just reverted to the /= 4 because we had that for a long time and it
> seemed to work. I don't really mind either way as long as we get rid
> of that -3%. Do you have a suggestion?
>

How about simply using 3% of the root process's points so that root
processes get some bonus compared to non-root processes with the same
memory usage and it's scaled to the usage rather than amount of available
memory?

So rather than points /= 4, we do

if (has_capability_noaudit(p, CAP_SYS_ADMIN))
points -= (points * 3) / 100;

instead. Sound good?