Re: [PATCH 0/8] Create ZONE_MOVABLE to partition memory betweenmovable and non-movable pages

[Christoph Lameter]

On Mon, 29 Jan 2007, Andrew Morton wrote:

> > All 64 bit machine will only have a single zone if we have such a range 
> > alloc mechanism. The 32bit ones with HIGHMEM wont be able to avoid it, 
> > true. But all arches that do not need gymnastics to access their memory 
> > will be able run with a single zone.
> 
> What is "such a range alloc mechanism"?

As I mentioned above: A function that allows an allocation to specify 
which physical memory ranges are permitted.

> So please stop telling me what a wonderful world it is to not have multiple
> zones.  It just isn't going to happen for a long long time.  The
> multiple-zone kernel is the case we need to care about most by a very large
> margin indeed.  Single-zone is an infinitesimal corner-case.

We can still reduce the number of zones for those that require highmem to 
two which may allows us to avoid ZONE_DMA/DMA32 issues  and allow dma 
devices to avoid bunce buffers that can do I/O to memory ranges not 
compatible with the current boundaries of DMA/DMA32. And I am also 
repeating myself.

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