Re: [PATCH] slob: poor man's NUMA support.

From: Nish Aravamudan
Date: Tue Jun 26 2007 - 15:17:24 EST


On 6/26/07, Christoph Lameter <clameter@xxxxxxx> wrote:
On Tue, 26 Jun 2007, Nish Aravamudan wrote:

> > No. alloc_pages follows memory policy. alloc_pages_node does not. One of
> > the reasons that I want a new memory policy layer are these kinds of
> > strange uses.
>
> What would break by changing, in alloc_pages_node()
>
> if (nid < 0)
> nid = numa_node_id();
>
> to
>
> if (nid < 0)
> return alloc_pages_current(gfp_mask, order);
>
> beyond needing to make alloc_pages_current() defined if !NUMA too.

It would make alloc_pages_node obey memory policies instead of only
following cpuset constraints. An a memory policy may redirect the
allocation from the local node ;-).

heh, true true.

Hrm, I guess the simplest looking solution is rarely the best. Could
we add more smarts in alloc_pages_current() to make GFP_THISNODE be
equivalent to bind_zonelist(thisnode_only_mask)? I'll keep thinking,
maybe I'll come up with something.

Thanks,
Nish
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