Re: [PATCH] Remove OOM killer ...

[Marcelo Tosatti <marcelo.tosatti@cyclades.com>]

Hi Andries,

On Sat, Nov 06, 2004 at 01:53:17PM +0100, Andries Brouwer wrote:
> On Fri, Nov 05, 2004 at 06:01:18PM -0200, Marcelo Tosatti wrote:
> 
> > My wife is almost killing me, its Friday night and I've been telling her
> > "just another minute" for hours. Have to run.
> 
> :-)
> 
> > As you know the OOM is very problematic in 2.6 right now - so I went
> > to investigate it.
> 
> I have always been surprised that so few people investigated
> doing things right, that is, entirely without OOM killer.
> Apparently developers do not think about using Linux for serious work
> where it can be a disaster, possibly even a life-threatening disaster,
> when any process can be killed at any time.

Its just that the majority of users use total overcommit (the default), 
but you have a point.

> Ten years ago it was a bad waste of resources to have swapspace
> lying around that would be used essentially 0% of the time.
> But with todays disk sizes it is entirely feasible to have
> a few hundred MB of "unused" swap space. A small price to
> pay for the guarantee that no process will be OOM killed.
> 
> A month ago I showed a patch that made overcommit mode 2
> work for me. Google finds it in http://lwn.net/Articles/104959/
> 
> So far, nobody commented.
> 
> This is not in a state such that I would like to submit it,
> but I think it would be good to focus some energy into
> offering a Linux that is guaranteed free of OOM surprises.

I dont have any useful comments on patch on a quick look at it  - 
but yes non-overcommit should be working correctly.

> So, let me repeat the RFC.
> Apply the above patch, and do "echo 2 > /proc/sys/vm/overcommit_memory".
> Now test. In case you have no, or only a small amount of swap space,
> also do "echo 80 > /proc/sys/vm/overcommit_ratio" or so.

Will test your patch later on the weekend and take a slower look 
at it, hopefully with useful comments.