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Date: Thu, 01 Nov 2007 14:25:51 -0700 (PDT)
Message-Id: <20071101.142551.93114462.davem@davemloft.net>
To: clameter@sgi.com
Cc: dada1@cosmosbay.com, akpm@linux-foundation.org, linux-arch@vger.kernel.org,
       linux-kernel@vger.kernel.org, mathieu.desnoyers@polymtl.ca,
       penberg@cs.helsinki.fi
Subject: Re: [patch 0/7] [RFC] SLUB: Improve allocpercpu to reduce per cpu
 access overhead
From: David Miller <davem@davemloft.net>
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From: Christoph Lameter <clameter@sgi.com>
Date: Thu, 1 Nov 2007 06:01:14 -0700 (PDT)

> On Thu, 1 Nov 2007, David Miller wrote:
> 
> > IA64 seems to use it universally for every __get_cpu_var()
> > access, so maybe it works out somehow :-)))
> 
> IA64 does not do that. It addds the local cpu offset
> 
> #define __get_cpu_var(var) (*RELOC_HIDE(&per_cpu__##var, 
> __ia64_per_cpu_var(local_per_cpu_offset)))
> #define __raw_get_cpu_var(var) (*RELOC_HIDE(&per_cpu__##var, 
> __ia64_per_cpu_var(local_per_cpu_offset)))

Oh I see, it's the offset itself which is accessed at the fixed
virtual address slot.