Re: [PATCH] strict VM overcommit accounting for 2.4.32/2.4.33-pre1

[Willy Tarreau <willy@w.ods.org>]

On Fri, Dec 30, 2005 at 07:17:46PM +0100, Arjan van de Ven wrote:
> On Fri, 2005-12-30 at 18:48 +0100, Willy Tarreau wrote:
> > On Thu, Dec 29, 2005 at 11:44:01PM -0800, Barry K. Nathan wrote:
> > > This patch adds strict VM overcommit accounting to the mainline 2.4
> > > kernel, thus allowing overcommit to be truly disabled. This feature
> > > has been in 2.4-ac, Red Hat Enterprise Linux 3 (RHEL 3) vendor kernels,
> > > and 2.6 for a long while.
> > 
> > Many thanks, I'm impatient to try it ! I tried to backport it in the
> > past but miserably failed as I don't understand those areas well. I'm
> > interested in checking that a buggy service cannot eat all the RAM an
> > bring the machine to death.
> 
> that's what rlimit is for though... overcommit acounting doesn't help
> you a lot there.

Not always. When you have buggy apache modules eating lots of memory and
you have tons of processes, rlimit will be of limited help.

> Also I think, to be honest, that this is a feature that is getting
> unsuitable for the "bugfixes only" 2.4 kernel series....

Agreed, it really is too late IMHO, because there's a non-null risk of
introducing new bugs with it. It would have been cool a few months
earlier. That won't stop me from trying it in my own tree however ;-)

Willy