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Date: Wed, 16 Apr 2003 13:35:39 -0700
From: Andrew Morton <akpm@digeo.com>
To: Matthew Wilcox <willy@debian.org>
Cc: ak@muc.de, willy@debian.org, davem@redhat.com,
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       davidm@hpl.hp.com, matthew@wil.cx, ralf@linux-mips.org, rth@redhat.com
Subject: Re: Reduce struct page by 8 bytes on 64bit
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Matthew Wilcox <willy@debian.org> wrote:
>
> Jacob's would break if we hashed to different spinlocks.  But we don't, we
> shift right by 8, so we get the same spinlock for atomic things that are on
> the same "cacheline" (i think PA cachelines are actually 64 or 128 bytes,
> depending on model).
> 

Are you prepared to cast this in stone?

If so then I think Jacob's approach would be preferable, don't you agree?

It needs some compiler-detection magic around the anon union though.