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Date: Wed, 22 Apr 2009 11:12:26 +0200
From: Ingo Molnar <mingo@elte.hu>
To: David Howells <dhowells@redhat.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
       Thomas Gleixner <tglx@linutronix.de>, "H. Peter Anvin" <hpa@zytor.com>,
       Linus Torvalds <torvalds@linux-foundation.org>, tj@kernel.org,
       akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
       Rusty Russell <rusty@rustcorp.com.au>,
       Fenghua Yu <fenghua.yu@intel.com>,
       Suresh Siddha <suresh.b.siddha@intel.com>
Subject: Re: [PATCH] FRV: Fix the section attribute on UP DECLARE_PER_CPU()
Message-ID: <20090422091226.GA18226@elte.hu>
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* David Howells <dhowells@redhat.com> wrote:

> Any idea what this:
> 
> 	#define DEFINE_PER_CPU_SHARED_ALIGNED(type, name)
> 
> is intended for?

it is a mixed type of percpu variable: which is per CPU but which 
can (and will) also be accessed from other CPUs. This way we 
basically cache-line align it and make sure nearby percpu variables 
dont get caught up in any cacheline bounces. It was introduced a 
couple of years ago.

	Ingo