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From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Jon Tollefson <kniht@linux.vnet.ibm.com>
Subject: Re: SL*B: drop kmem cache argument from constructor
Date: Mon, 14 Jul 2008 14:48:21 +1000
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Cc: Andrew Morton <akpm@linux-foundation.org>,
       Alexey Dobriyan <adobriyan@gmail.com>, penberg@cs.helsinki.fi,
       mpm@selenic.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org,
       cl@linux-foundation.org
References: <20080710011132.GA8327@martell.zuzino.mipt.ru> <20080711122228.eb40247f.akpm@linux-foundation.org> <4877D35E.8080209@linux.vnet.ibm.com>
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On Saturday 12 July 2008 07:40, Jon Tollefson wrote:
> Andrew Morton wrote:

> > btw, Nick, what's with that dopey
> >
> > 	huge_pgtable_cache(psize) = kmem_cache_create(...
> >
> > trick?  The result of a function call is not an lvalue, and writing a
> > macro which pretends to be a function and then using it in some manner
> > in which a function cannot be used is seven ways silly :(

I agree it isn't nice.


> That silliness came from me.
> It came from my simplistic translation of the existing code to handle
> multiple huge page sizes.  I would agree it would be easier to read and
> more straight forward to just have the indexed array directly on the
> left side instead of a macro.  I can send out a patch that makes that
> change if desired.
> Something such as
>
> +#define HUGE_PGTABLE_INDEX(psize) (HUGEPTE_CACHE_NUM + psize - 1)
>
> -huge_pgtable_cache(psize) = kmem_cache_create(...
> +pgtable_cache[HUGE_PGTABLE_INDEX(psize)] = kmem_cache_create(...
>
>
> or if there is a more accepted way of handling this situation I can
> amend it differently.

If it is a once off initialization (which it is), that's probably fine
like that. Otherwise, the convention is to have a set_huge_pgtable_cache
function as well. But whatever you prefer. Yes if you can send a patch,
that would be good, thanks.
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