Re: [RFC] Optimization for use-once pages

Marcelo Tosatti (marcelo@conectiva.com.br)
Tue, 24 Jul 2001 17:53:36 -0300 (BRT)


On Tue, 24 Jul 2001, Rik van Riel wrote:

> On Tue, 24 Jul 2001, Marcelo Tosatti wrote:
> > On Tue, 24 Jul 2001, Daniel Phillips wrote:
> >
> > > Today's patch tackles the use-once problem, that is, the problem of
> >
> > Well, as I see the patch should remove the problem where
> > drop_behind() deactivates pages of a readahead window even if
> > some of those pages are not "used-once" pages, right ?
> >
> > I just want to make sure the performance improvements you're
> > seeing caused by the fix of this _particular_ problem.
>
> Fully agreed.
>
> Especially since it was a one-liner change from worse
> performance to better performance (IIRC) it would be
> nice to see exactly WHY the system behaves the way it
> does. ;)

Yes.

Daniel's patch adds "drop behind" (that is, adding swapcache
pages to the inactive dirty) behaviour to swapcache pages.

This is a _new_ thing, and I would like to know how that is changing the
whole VM behaviour..

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