Re: [PATCH 3/4] Embed zone_id information within the zonelist->zones pointer

Andi Kleen
2007-08-14T00:26:35Z

On Mon, Aug 13, 2007 at 04:27:42PM -0700, Christoph Lameter wrote:
> On Tue, 14 Aug 2007, Andi Kleen wrote:
>
> > > Ok then lets do it.
> >
> > Conversion only makes sense once an API with a explicit mask
> > is in. Otherwise we have muddled semantics again.
>
> pci_set_consistent_dma_mask
>
> has that.

While on x86 it is roughly identical (although the low level
allocator is currently not very reliable) it makes a significant
difference on some platforms. e.g. I was told on PA-RISC
consistent memory is much more costly than non consistent ones.
That's probably true on anything that's not full IO cache
consistent.

So while it would be reasonable semantics for x86 and IA64
it's not for everybody else.

-Andi