http://lwn.net/Articles/4628/ has this possibly useful info:
--------------- So what is strict VM overcommit? We introduce new overcommit policies that attempt to never succeed an allocation that can not be fulfilled by the backing store and consequently never OOM. This is achieved through strict accounting of the committed address space and a policy to allow/refuse allocations based on that accounting. In the strictest of modes, it should be impossible to allocate more memory than available and impossible to OOM. All memory failures should be pushed down to the allocation routines -- malloc, mmap, etc. -------------- But see also the discussion from July last year:http://www.ussg.iu.edu/hypermail/linux/kernel/0207.2/index.htmlA quick investigation of 2.4 releases on kernel.org appears to show this still hasn't made it into mainline kernels. Apparently Alan did this work originally because RH had customers using Oracle who were running into OOM ... Surprise!I don't keep copies of old kernel sources around on my Linux machine, so I don't know when it went into the RH kernel series - that at least would be nice to know.andrew ----- Original Message ----- From: "Andrew Dunstan" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Saturday, June 14, 2003 12:30 PM Subject: Re: [HACKERS] Pre-allocation of shared memory ... > The trouble with this advice is that if I am an SA wanting to run a DBMS > server, I will want to run a kernel supplied by a vendor, not an arbitrary > kernel released by a developer, even one as respected as Alan Cox. > > andrew > > ----- Original Message ----- > From: "Lamar Owen" <[EMAIL PROTECTED]> > To: "Nigel J. Andrews" <[EMAIL PROTECTED]> > Cc: "Josh Berkus" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> > Sent: Saturday, June 14, 2003 11:52 AM > Subject: Re: [HACKERS] Pre-allocation of shared memory ... > > > > On Friday 13 June 2003 15:29, Lamar Owen wrote: > > > It is or was a Linux kernel problem. The 2.2 kernel required double > swap > > > space, even though it wasn't well documented. Early 2.4 kernels also > > > required double swap space, and it was better documented. Current Red > Hat > > > 2.4 kernels, I'm not sure which VM system is in use. The old VM > certainly > > > DID require double physical memory swap space. > > > > After consulting with some kernel gurus, you can upgrade to a straight > Alan > > Cox (-ac) kernel and turn off overcommits to cause it to fail the > allocation > > instead of blowing processes out at random when the overcommit bites. > > > ---------------------------(end of broadcast)--------------------------- > TIP 9: the planner will ignore your desire to choose an index scan if your > joining column's datatypes do not match ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster