kernel killing processes when out of swap

Jim C. Nasby decibel at
Wed Apr 13 20:18:48 PDT 2005

On Wed, Apr 13, 2005 at 12:07:11AM +0200, Matthias Buelow wrote:
> Nick Barnes <Nick.Barnes at> writes:
> >> This stuff has been discussed in the past.
> >Indeed. For a couple of examples from the days before BSD systems got
> >overcommit, see these threads from 1990 and 1991:
> >
> ><
> >b658465/4c590978f1001507?q=overcommit&rnum=14#4c590978f1001507>
> >
> ><
> >6d30eb1/e8c30f78c44a3f62?q=overcommit&rnum=12#e8c30f78c44a3f62>
> Apparently, it can be turned off on AIX, quoting from
> ``If the PSALLOC environment variable is set to early, then every
> program started in that environment from that point on, but not
> including currently running processes, runs in the early allocation
> environment. In the early allocation environment, interfaces such as the
> malloc subroutine and the brk subroutine will fail if sufficient paging
> space cannot be reserved when the request is made.
> Processes run in the early allocation environment mode are not sent the
> SIGKILL signal if a low paging space condition occur.''
> Googling showed that on Linux 2.6, overcommit can be disabled globally
> through the vm.overcommit_memory sysctl.
> I hope that some day some mechanism to solve that problem will be
> available in FreeBSD aswell.

It's extremely disappointing that you can't turn this off. I've been
bashing linux for months now about how they think it's OK to kill random
processes. But at least they'll let you turn it off.
Jim C. Nasby, Database Consultant               decibel at 
Give your computer some brain candy! Team #1828

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