powerpc: Move 64bit heap above 1TB on machines with 1TB segments

[David Gibson]

On Wed, Sep 23, 2009 at 07:08:22AM +1000, Benjamin Herrenschmidt wrote:
> 
> > Unfortunately, I am not sensitive to issues surrounding 1TB segments or how
> > they are currently being used. However, as this clearly helps performance
> > for large amounts of memory, is it worth providing an option to
> > libhugetlbfs to locate 16MB pages above 1TB when they are otherwise being
> > unused?
> 
> AFAIK, that is already the case, at least the kernel will hand out pages
> above 1T preferentially iirc.
> 
> There were talks about making huge pages below 1T not even come up
> untily you ask for them with MAP_FIXED, dunno where that went.

That was already the case as far as I remember.  But it's just
possible that changed when the general slice handling code came in,

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson