Re: hugetlb demand paging patch part [2/3]

'David Gibson'
2004-04-16T06:15:42Z

On Thu, Apr 15, 2004 at 10:56:14PM -0700, Chen, Kenneth W wrote:
> David Gibson wrote on Thursday, April 15, 2004 9:49 PM
> > > > If we could get rid of follow_hugetlb_pages() it would remove an ugly
> > > > function from every arch, which would be nice.
> > >
> > > I hope the goal here is not to trim code for existing prefaulting scheme.
> > > That function has to go for demand paging, and demand paging comes with
> > > a performance price most people don't realize. If the goal here is to
> > > make the code prettier, I vote against that.
> >
> > Well, I'm attempting to understand the hugepage code across all the
> > archs, so that I can try to implement copy-on-write with a minimum of
> > arch specific gunk. Simplifying and consolidating the existing code
> > across archs would be a helpful first step, if possible.
>
> Looks like everyone has their own agenda, COW is related to demand paging,
> and has it's own set of characteristics to deal with. I would hope do one
> thing at a time.

Which is why I've attempted to factor things out of your patches which
don't appear to be inherent to demand paging. Consolidating the
existing hugepage code will make both demand-paging and COW patches
much more palatable.