Re: [RFC] Optimization for use-once pages

[Marcelo Tosatti]

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..