Subject: Re: [PATCH 0/7] [RFC] hugetlb: pagetable_operations API
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Adam Litke <agl@us.ibm.com>, linux-mm@kvack.org,
       linux-kernel@vger.kernel.org
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Date: Wed, 21 Feb 2007 06:57:40 +1100
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> maybe. I'm not entirely convinced... (I like the cleanup potential a lot
> code wise.. but if it costs performance, then... well I'd hate to see
> linux get slower for hugetlbfs)
> 
> > If not, then I definitely wouldn't
> > mind creating a default_pagetable_ops and calling into that.
> 
> ... but without it to be honest, your patch adds nothing real.. there's
> ONE user of your code, and there's no real cleanup unless you get rid of
> all the special casing.... since the special casing is the really ugly
> part of hugetlbfs, not the actual code inside the special case..

Well... I disagree there too :-)

I've been working recently for example on some spufs improvements that
require similar tweaking of the user address space as hugetlbfs. The
problem I have is that while there are hooks in the generic code pretty
much everywhere I need.... they are all hugetlb specific, that is they
call directly into the hugetlb code.

For now, I found ways of doing my stuff without hooking all over the
page table operations (well, I had no real choices) but I can imagine it
making sense to allow something (hugetlb being one of them) to take over
part of the user address space.

Ben.


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