Re: Discussion on my OOM killer API

[James Sutherland <jas88@cam.ac.uk>]

On Thu, 26 Oct 2000, Rik van Riel wrote:

> On Thu, 26 Oct 2000, Linus Torvalds wrote:
> > On Thu, 19 Oct 2000, Rik van Riel wrote:
> > > > I'm also willing to maintain it ;-)
> > > 
> > > Linus, how would you feel about an interface that allows
> > > people to insomd/rmmod their own OOM handler ?
> > 
> > I hate the idea.
> 
> *grin*
> 
> I agree with that, except for one small point...

I agree too: if we're out of memory hard enough to trigger the in-kernel
handler, blowing away almost anything would be an improvement. Ideally,
action should be taken by userspace long before this point...

> > I dislike that kind of approach in general. I don't like plug-in
> > schedulers, etc either. I think it's a cop-out, saying that we
> > cannot do a good enough job, and claiming that it's such a
> > difficult problem that we should let the user decide.
> 
> ... the generic OOM killer we have in the system right now
> should do a good job in most of the cases, but I've heard
> from a number of people who would like to have the OOM killer
> do something "special" for their system.
> 
> For instance, they want to have student programs killed before
> staff programs, or want to be able to specify some priveledged
> processes that will never be killed (or do other things that
> we probably don't want to have in the generic killer).
> 
> > In short, it's one of those things that sounds like a good idea,
> > but that results in absolute crap in the end.
> 
> Sure, but the idea is to keep this absolute crap out of
> the kernel and local to the systems where people need
> to replace the OOM killer because of special reasons ;)

Which begs the question, where did the userspace OOM policy daemon go? It,
coupled with Rik's simple in-kernel last-ditch handler, should cover most
eventualities without the need for nasty kernel kludges.


James.

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