Re: [rfc][patch 2/3] slab: introduce SMP alignment

Nick Piggin
2008-03-07T04:37:24Z

On Mon, Mar 03, 2008 at 01:31:14PM -0800, Christoph Lameter wrote:
> On Mon, 3 Mar 2008, Nick Piggin wrote:
>
> > And maybe the VSMP guys will want to blow this out to their internode
> > alignment?
> >
> > max(!CONFIG_TINY && num_possible_cpus() > 1 ? (is_vsmp ? internode_alignemnt : cache_line_size()) : 0, mandatory_alignment)
>
> No the slab allocators were optimized for VSMP so that the
> internode_alignment is not necessary there. That was actually one of the
> requirements that triggered the slab numa work.

BTW. can you explain this incredible claim that the slab allocators
do not need internode_alignment to avoid false sharing of allocated
objects on VSMP? I don't understand how that would work at all.