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Date: Thu, 19 Dec 2013 09:21:15 -0600 (CST)
From: Christoph Lameter <cl@linux.com>
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To: Dave Hansen <dave@sr71.net>
cc: Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, Pravin B Shelar <pshelar@nicira.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Andi Kleen <ak@linux.intel.com>, Pekka Enberg <penberg@kernel.org>
Subject: Re: [RFC][PATCH 0/7] re-shrink 'struct page' when SLUB is on.
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On Wed, 18 Dec 2013, Dave Hansen wrote:

> On 12/18/2013 04:41 PM, Andrew Morton wrote:
> >> > Unless somebody can find some holes in this, I think we have no choice
> >> > but to unset the HAVE_ALIGNED_STRUCT_PAGE config option and revert using
> >> > the cmpxchg, at least for now.
> >
> > So your scary patch series which shrinks struct page while retaining
> > the cmpxchg_double() might reclaim most of this loss?
>
> That's what I'll test next, but I hope so.
>
> The config tweak is important because it shows a low-risk way to get a
> small 'struct page', plus get back some performance that we lost and
> evidently never noticed.  A distro that was nearing a release might want
> to go with this, for instance.

Ok then lets just drop the cmpxchg updates to the page struct. The
spinlock code is already in there so just removing the __CMPXCHG flag
related processing should do the trick.