Re: [PATCH 03/10] mm: tag reseve pages

Matt Mackall
2007-08-06T19:38:42Z

On Mon, Aug 06, 2007 at 12:10:53PM -0700, Andrew Morton wrote:
> On Mon, 6 Aug 2007 20:59:26 +0200 Andi Kleen <andi@firstfloor.org> wrote:
>
> > > precious page flag
> >
> > I always cringe when I hear that. It's really more than node/sparsemem
> > use too many bits. If we get rid of 32bit NUMA that problem would be
> > gone for the node at least because it could be moved into the mostly
> > unused upper 32bit part on 64bit architectures.
>
> Removing 32-bit NUMA is attractive - NUMAQ we can probably live without,
> not sure about summit. But superh is starting to use NUMA now, due to
> varying access times of various sorts of memory, and one can envisage other
> embedded setups doing that.
>
> Plus I don't think there are many flags left in the upper 32-bits. ia64
> swooped in and gobbled lots of them, although it's not immediately clear
> how many were consumed.
>
> > The alternative would be to investigate again what it does to the
> > kernel to just use different lookup methods for this.
>
> That's cringeworthy too, I expect.

Perhaps the node info could be pulled out into a parallel and
effectively read-only array of shorts.

--
Mathematics is the supreme nostalgia of our time.