[clug] Swap priority on 2.6 kernel

[Martin Pool]

On 15 Aug 2004, Andrew Pollock <me at andrew.net.au> wrote:
> On Sat, Aug 14, 2004 at 08:51:03AM +1000, Martin Pool wrote:
> > On 14 Aug 2004, Nigel Cunningham <ncunningham at linuxmail.org> wrote:
> > 
> > > For 2.6, it's probably best not to use swap.
> > 
> > Why do you say that?
> > 
> 
> Just read your blog on the topic. Nice read. Is it 2.4 specific or in
> general? I was under the impression that 2.6 had a VM overhaul.

swap has been used for anonymous memory for a long time, certainly
back to 2.4.  I think Linux has always had this design.

The decisions about which pages to pull in and out when have changed,
but the places they go to and from have not.

Having no swap is equivalent to setting a "never page anonymous
memory" option.  If you had such a flag, would you want to set it?

You might if you thought that anonymous memory was far more valuable
than file-backed memory, but I don't see why that would be true.

Or you might set it if you thought the VM system worked well for
file-backed memory but poorly for anonymous memory, but I don't think
that's true either.  The vm is not perfect but I don't think it's
worse at anonymous memory than file-backed memory.

For more details

  http://kerneltrap.org/node/view/3202

--
Martin
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