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

Christoph Lameter
2007-06-26T18:14:27Z

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.

>
> if (node < 0
>
> rather than comparing with -1 exactly.
>
> On many CPUs it'll save a few bytes of code.

-1 means no node specified and much of the NUMA code compares with -1.