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SubjectRe: [RFC PATCH] mm: introduce N_LRU_MEMORY to distinguish between normal and movable memory
On Fri, 10 Aug 2012, Hanjun Guo wrote:

> On 2012/8/9 22:06, Christoph Lameter (Open Source) wrote:
> > On Thu, 9 Aug 2012, Hanjun Guo wrote:
> >
> >> Now, We have node masks for both N_NORMAL_MEMORY and
> >> N_HIGH_MEMORY to distinguish between normal and highmem on platforms such as x86.
> >> But we still don't have such a mechanism to distinguish between "normal" and "movable"
> >> memory.
> >
> > What is the exact difference that you want to establish?
>
> Hi Christoph,
> Thanks for your comments very much!
>
> We want to identify the node only has ZONE_MOVABLE memory.
> for example:
> node 0: ZONE_DMA, ZONE_DMA32, ZONE_NORMAL--> N_LRU_MEMORY, N_NORMAL_MEMORY
> node 1: ZONE_MOVABLE --> N_LRU_MEMORY
> thus, in SLUB allocator, will not allocate memory control structures for node1.

So this would change the N_NORMAL_MEMORY definition so that N_NORMAL
means !LRU allocs possible? So far N_NORMAL_MEMORY has a wider scope of
meaning. We need an accurate definition of the meaning of all these
attributes.

> > For the slab case that you want to solve here you will need to know if the
> > node has *only* movable memory and will never have any ZONE_NORMAL memory.
> > If so then memory control structures for allocators that do not allow
> > movable memory will not need to be allocated for these node. The node can
> > be excluded from handling.
>
> I think this is what we are trying to do in this patch.
> did I miss something?

THe meaning of ZONE_NORMAL seems to change which causes confusion. Please
describe in detail what each of these attributes mean.


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