[CentOS] what would be happen if swap partition is not?

[Kwan Lowe]

On Fri, Jul 3, 2009 at 11:11 PM, Keith Keller <kkeller at 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outdated information and some that's not just outdated, but was never right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.
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