[RFC PATCH -V2 05/21] powerpc: Reduce PTE table memory wastage

[David Gibson]

On Thu, Feb 21, 2013 at 10:17:12PM +0530, Aneesh Kumar K.V wrote:
> From: "Aneesh Kumar K.V" <aneesh.kumar at linux.vnet.ibm.com>
> 
> We now have PTE page consuming only 2K of the 64K page.This is in order to
> facilitate transparent huge page support, which works much better if our PMDs
> cover 16MB instead of 256MB.
> 
> Inorder to reduce the wastage, we now have multiple PTE page fragment
> from the same PTE page.

This needs a much better description of what you're doing here to
manage the allocations.  It's certainly not easy to figure out from
the code.


[snip]
> +#ifdef CONFIG_PPC_64K_PAGES
> +typedef pte_t *pgtable_t;
> +#else
>  typedef struct page *pgtable_t;
> +#endif

This looks really bogus.  A pgtable_t is a pointer to PTEs on 64K, but
a pointer to a struct page on 4k.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson
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