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SubjectRe: [PATCH] you have how many nodes??
jbarnes@sgi.com (Jesse Barnes) wrote:
>
> Needed this for booting on a 128 node system.
>
> -#define ZONE_SHIFT (BITS_PER_LONG - 8)
> +#define ZONE_SHIFT (BITS_PER_LONG - 10)

eeek, ia32 just lost another two page flags.

This stuff needs to be controlled by per-arch and per-subarch header files.

Instead of going backwards like this we'd like to actually free up _more_
bits in page->flags. The worst (and controlling) case is on 32-bit NUMA:
eight nodes, three zones per node. That's five bits, leaving us 27 page
flags.

So we'd need

include/asm-foo/zonestuff.h:

#define ARCH_MAX_NODES_SHIFT 3 /* Up to 8 nodes */
#define ARCH_MAX_ZONES_SHIFT 2 /* Up to 4 zones per node */


and all the mm.h/mmzone.h constants use those two.


I think. We could just say "dang numaq needs five bits", so:


#if BITS_PER_LONG == 32
#define ZONE_SHIFT 5
#else
#define ZONE_SHIFT 10
#endif


Bit sleazy, but I think that would suffice.
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