Re: [patch 11/21] Xen-paravirt: Add apply_to_page_range() which applies a function to a pte range.

Andrew Morton
2007-02-16T07:20:46Z

On Thu, 15 Feb 2007 23:06:45 -0800 Jeremy Fitzhardinge <jeremy@goop.org> wrote:

> Andrew Morton wrote:
> > On Thu, 15 Feb 2007 18:25:00 -0800 Jeremy Fitzhardinge <jeremy@goop.org> wrote:
> >
> >
> >> Add a new mm function apply_to_page_range()[...]
> > There was some discussion about this sort of thing last week. The
> > consensus was that it's better to run the callback against a whole pmd's
> > worth of ptes, mainly to amortise the callback's cost (a lot).
> >
> > It was implemented in
> > ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.20/2.6.20-mm1/broken-out/smaps-extract-pmd-walker-from-smaps-code.patch
>
> Yes I was looking at that and wondering what the upshot would be. I'll
> have a closer look, but it seems like it should be usable.

It's a question of who-merges-first. I wasn't planning on merging the
smaps stuff into 2.6.21.

Perhaps the best approach is to proceed as-is and clean things up once it's
all merged.

I guess your pte-at-a-time walker could be quite simply implemented underneath
the smaps pmd-at-a-time walker.