Re: Page allocator: Single Zone optimizations

[Christoph Lameter <clameter@sgi.com>]

On Wed, 1 Nov 2006, Andrew Morton wrote:

> And hot-unplug isn't actually the interesting application.  Modern Intel
> memory controllers apparently have (or will have) the ability to power down
> DIMMs.

Plus one would want to be able to move memory out of an area where we may 
have a bad DIMM. If we monitor soft ECC failures then we could also 
judge a DIMM to be bad if we have a too high soft failure rate.

If there is a hard failure and we can recover (page cache page f.e.) 
then we could preemptively disable the complete DIMM.

I still think that we need to generalize the approach to be 
able to cover as much memory as possible. Remapping can solve some of the 
issues, for others we could add additional ways to make things movable. 
F.e. one could make page table pages movable by adding a back pointer to 
the mm, reclaimable slab pages by adding a move function, driver 
allocations could have a backpointer to the driver that would be able to 
move its memory.  Hmm.... Maybe generally a way to provide a 
function to move data in the page struct for kernel allocations?

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