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Date: Wed, 30 Mar 2011 08:58:23 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Andi Kleen <andi@firstfloor.org>
CC: Tejun Heo <tj@kernel.org>, Ingo Molnar <mingo@elte.hu>,
        Thomas Gleixner <tglx@linutronix.de>, x86@kernel.org,
        Christoph Lameter <cl@linux.com>, linux-kernel@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Pekka Enberg <penberg@kernel.org>
Subject: Re: [PATCH tip:x86/mm 1/3] x86: A fast way to check capabilities
 of the current cpu
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On 03/14/2011 12:49 PM, Andi Kleen wrote:
> Tejun Heo <tj@kernel.org> writes:
> 
>> Add this_cpu_has() which determines if the current cpu has a certain
>> ability using a segment prefix and a bit test operation.
> 
> 
> Hmm: if the CPU capability is really tested in a performance critical
> path, wouldn't it even be better to just use static_branch() now? 
> 

We have static_cpu_has() for this specific purpose (it actually predates
static_branch()).

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.