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

From: Nish Aravamudan
Date: Tue Jun 26 2007 - 15:04:30 EST


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

> > +#ifdef CONFIG_NUMA
> > + if (node != -1)
> > + page = alloc_pages_node(node, gfp, order);
> > + else
> > +#endif
> > + page = alloc_pages(gfp, order);
>
> Isn't the above equivalent to a bare
>
> page = alloc_pages_node(node, gfp, order);
>
> ?

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.

Thanks,
Nish
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