Re: ZONE_DMA

[Jesse Barnes <jesse.barnes@intel.com>]

On Friday, September 22, 2006 11:40 am, Christoph Lameter wrote:
> On Fri, 22 Sep 2006, Jesse Barnes wrote:
> > Right, the internals are arch specific and don't necessarily have to
> > rely on a zone, depending on their DMA constraints.
>
> From what I can see the arch specific do some tricks and then pick
> GFP_DMA or something to get memory that is appropriately limited. Having
> the ability to retrieve pages from a certain range from the page
> allocator would fix this issue and improve the ability of devices to
> allocate memory.

Right, being able to allocate from specific ranges would obviate the need 
for GFP_DMA and the various zones.  It would come with a cost though since 
the VM would have to become aware of pressure at various ranges rather 
than just on zones like we have now.  I think that's where things get 
tricky.

Jesse