Re: [Patch] New zone ZONE_EASY_RECLAIM take 4. (change build_zonelists)[3/8]

[Joel Schopp <jschopp@austin.ibm.com>]

> -	BUG_ON(zone_type > ZONE_HIGHMEM);
> +	BUG_ON(zone_type > ZONE_EASY_RECLAIM);

It might be nice to check ifndef CONFIG_HIGHMEM that the zone isn't 
particularly ZONE_HIGHMEM.

>  	int res = ZONE_NORMAL;
> -	if (zone_bits & (__force int)__GFP_HIGHMEM)
> -		res = ZONE_HIGHMEM;
> -	if (zone_bits & (__force int)__GFP_DMA32)
> -		res = ZONE_DMA32;
> -	if (zone_bits & (__force int)__GFP_DMA)
> +
> +	if (zone_bits == fls((__force int)__GFP_DMA))
>  		res = ZONE_DMA;
> +	if (zone_bits == fls((__force int)__GFP_DMA32) &&
> +	    (__force int)__GFP_DMA32 == 0x02)
> +		res = ZONE_DMA32;
> +	if (zone_bits == fls((__force int)__GFP_HIGHMEM))
> +		res = ZONE_HIGHMEM;
> +	if (zone_bits == fls((__force int)__GFP_EASY_RECLAIM))
> +		res = ZONE_EASY_RECLAIM;
> +
>  	return res;
>  }

It is incredibly silly to check a constant for a value.  When it is zero 
instead of 2 the first part of the statement will be false anyway.

Which reminds me.  Why are we using fls again?  I don't see why we 
aren't just (zone_bits & value) the types.  It seems much easier to 
understand that way.

>  
> Index: zone_reclaim/include/linux/gfp.h
> ===================================================================
> --- zone_reclaim.orig/include/linux/gfp.h	2005-12-19 20:19:37.000000000 +0900
> +++ zone_reclaim/include/linux/gfp.h	2005-12-19 20:19:56.000000000 +0900
> @@ -81,7 +81,7 @@ struct vm_area_struct;
>  
>  static inline int gfp_zone(gfp_t gfp)
>  {
> -	int zone = GFP_ZONEMASK & (__force int) gfp;
> +	int zone = fls(GFP_ZONEMASK & (__force int) gfp);
>  	BUG_ON(zone >= GFP_ZONETYPES);
>  	return zone;
>  }


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