Re: [RFC] Limit the size of the pagecache

[Aubrey Li]

On 1/24/07, Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote:
> On Tue, 2007-01-23 at 16:49 -0800, Christoph Lameter wrote:
> > This is a patch using some of Aubrey's work plugging it in what is IMHO
> > the right way. Feel free to improve on it. I have gotten repeatedly
> > requests to be able to limit the pagecache. With the revised VM statistics
> > this is now actually possile. I'd like to know more about possible uses of
> > such a feature.
> >
> >
> >
> >
> > It may be useful to limit the size of the page cache for various reasons
> > such as
> >
> > 1. Insure that anonymous pages that may contain performance
> >    critical data is never subject to swap.
>
> This is what we have mlock for, no?
>
> > 2. Insure rapid turnaround of pages in the cache.
>
> This sounds like we either need more fadvise hints and/or understand why
> the VM doesn't behave properly.
>
> > 3. Reserve memory for other uses? (Aubrey?)
>
> He wants to make a nommu system act like a mmu system; this will just
> never ever work.

Nope. Actually my nommu system works great with some of patches made by us.
What let you think this will never work?

> Memory fragmentation is a real issue not some gimmick
> thought up by the hardware folks to sell these mmu chips.
I totally disagree. Memory fragmentations is the issue not only on
nommu, it's also on mmu chips. That's not the reason mmu chips can be
sold.

-Aubrey
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