Re: [PATCH] remove zone_mem_map

[Christoph Lameter <clameter@engr.sgi.com>]

On Wed, 22 Feb 2006, KAMEZAWA Hiroyuki wrote:

> This patch removes zone_mem_map.

Note that IA64 does not seem to depend on zone_mem_map...

> Index: test/include/asm-generic/memory_model.h
> ===================================================================
> --- test.orig/include/asm-generic/memory_model.h
> +++ test/include/asm-generic/memory_model.h
> @@ -47,9 +47,9 @@ extern unsigned long page_to_pfn(struct
> 
>  #define page_to_pfn(pg)			\
>  ({	struct page *__pg = (pg);		\
> -	struct zone *__zone = page_zone(__pg);	\
> -	(unsigned long)(__pg - __zone->zone_mem_map) +	\
> -	 __zone->zone_start_pfn;			\
> +	struct pglist_data *__pgdat = NODE_DATA(page_to_nid(__pg));	\
> +	(unsigned long)(__pg - __pgdat->node_mem_map) +	\
> +	 __pgdat->node_start_pfn;			\
>  })

NODE_DATA is an arch specific lookup, If it always is a table lookup
then the performance will be comparable to page_zone because that also 
involves one table lookup.
-
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