On Fri, Jul 3, 2009 at 11:11 PM, Keith Keller <kkeller@speakeasy.net> wrote:

On Fri, Jul 03, 2009 at 02:18:57PM -0400, Kwan Lowe wrote:
>
> If you do run without page space, you should configure the kernel overcommit
> options.

Is there a good, consistent, complete source of documentation for these
options? They have changed a bunch in the 2.6 kernels, and I suspect
the docs in the kernel source were not always up to date with the
available options.

I agree. Just doing a quick search and found that there's a bunch of outdated information and some that's not just outdated, but was never right in the first place.

For example, take a look at page volumes versus page files... Traditionally you would use a page volume because of the overhead involved with using files. Then changes to how page files were used made the difference almost (or completely) negligible. But then fragmentation may come into play when creating page files so page volumes would still be better.. But then storage is often virtualized so it again may not matter because the backing volume itself may be fragmented, or in some cases, reside on multiple physical volumes so it didn't matter. And with new allocation routines, maybe it again doesn't matter.

Here's one decent guide that explains what happens in an OOM situation:

http://www.linuxdevcenter.com/pub/a/linux/2006/11/30/linux-out-of-memory.html

There's also some good stuff on kerneltrap.org.