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

[Christoph Lameter]

On Sat, 11 Aug 2007, Andi Kleen wrote:

> > Hallelujah. You are my hero! x86_64 will switch off CONFIG_ZONE_DMA?
> 
> Yes. i386 too actually.
> 
> The DMA zone will be still there, but only reachable with special functions.

Not too happy with that one but this is going the right direcrtion.

On NUMA this would still mean allocating space for the DMA zone on all 
nodes although we only need this on node 0.

> Also all callers are going to pass masks around so it's always clear
> what address range they really need. Actually a lot of them
> pass still 16MB simply because it is hard to find out what masks
> old undocumented hardware really needs. But this could change.

Good.

> This also means the DMA support in sl[a-z]b is not needed anymore.

Tell me when. SLUB has an #ifdef CONFIG_ZONE_DMA. We can just drop that 
code in the #ifdef's if you are ready.

> I went through near all GFP_DMA users and found they're usually
> happy enough with pages. If someone comes up who really needs
> lots of subobjects the right way for them would be likely extending
> the pci pool allocator for this case. But I haven't found a need for this yet.

Great.
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