Re: HOLES_IN_ZONE...

[Heiko Carstens]

On Thu, 05 Feb 2009 15:44:03 -0800 (PST)
David Miller <davem@xxxxxxxxxxxxx> wrote:

> > Later I reduced MAX_ORDER to 9 on s390, so we don't leave large
> > portions of memory unused.
> 
> Isn't is easier to just make sure your vmemmap mappings extend to such
> boundaries, whether they contain available memory or not?
> 
> That's the only requirement you have to satisfy to avoid having to
> specify HOLES_IN_ZONE.  You don't have to have memory there, just
> some vmmemmap page structs have to be mapped at those indices.
> 
> And then you won't need waste memory with these MAX_ORDER boundary
> adjustments.

Sounds reasonable. Back then I was under the impression that it is not
sufficient to only have a struct page but also a page for each PFN.
I'll give it a try as soon as time permits.

Thanks!
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