Huge pages

[Tiago Stürmer Daitx]

> On Thu, 2013-04-11 at 16:26 +0200, Volker Simonis wrote:
> 
> > I think it will be not trivial to get this working with all the
> > combinations of different GCs and +/- compressed oops on all Linux
> > architectures.
> > 
> > It would be really great if you could find sombody from the LTC who
> > can explain why mmap with MAP_HUGETLB behaves differently on x86 and
> > ppc.

Volker, I got the following response from a PPC Kernel dev:

'On ppc64, you can only have one page size in a "slice".  Slices are
256M below 4G, then 4G-1TB then 1TB slices above that.  Since the
MAP_NORESERVE is not a hugepage mapping, it is not being placed to
accomodate these restrictions. Overmapping with MAP_FIXED is then
failing.'

Let me know if you need additional information on this issue.

-- 
Tiago Stürmer Daitx
tdaitx at linux.vnet.ibm.com
IBM - Linux Technology Center