[added linux-arch to cc since we're going to be affecting them]
On Wed, 2011-04-20 at 14:28 +0300, Pekka Enberg wrote:
> Right. My point was simply that since x86 doesn't support DISCONTIGMEM
> without NUMA, the misunderstanding is likely very wide-spread.
Why don't we approach the problem in a few separate ways then.
1. We can look at what imposing NUMA on the DISCONTIGMEM archs
would do ... the embedded ones are going to be hardest hit, but
if it's not too much extra code, it might be palatable.
2. The other is that we can audit mm to look at all the node
assumptions in the non-numa case. My suspicion is that
accidentally or otherwise, it mostly works for the normal case,
so there might not be much needed to pull it back to working
properly for DISCONTIGMEM.
3. Finally we could look at deprecating DISCONTIGMEM in favour of
SPARSEMEM, but we'd still need to fix -stable for that case.
Especially as it will take time to convert all the architectures
I'm certainly with Matthew: DISCONTIGMEM is supposed to be a lightweight
framework which allows machines with split physical memory ranges to
work. That's a very common case nowadays. Numa is supposed to be a
heavyweight framework to preserve node locality for non-uniform memory
access boxes (which none of the DISCONTIGMEM && !NUMA systems are).
James
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