linux-kernel - Re: [PATCH 2/5] powernow-k8: Add core performance boost support

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Date:	Tue, 23 Mar 2010 15:19:34 +0100
From:	Borislav Petkov <bp@...64.org>
To:	Dominik Brodowski <linux@...inikbrodowski.net>
Cc:	Thomas Renninger <trenn@...e.de>, akpm@...ux-foundation.org,
	davej@...hat.com, cpufreq@...r.kernel.org, x86@...nel.org,
	linux-kernel@...r.kernel.org, "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH 2/5] powernow-k8: Add core performance boost support

From: Dominik Brodowski <linux@...inikbrodowski.net>
Date: Tue, Mar 23, 2010 at 02:27:37PM +0100

Hi Dominik,

> On Tue, Mar 23, 2010 at 12:58:58PM +0100, Borislav Petkov wrote:
> > > It could already be set in arch/x86/kernel/cpu/amd.c and
> > > powernow-k8 could use cpu_has(cpu, X86_FEATURE_CPB);
> > 
> > I'd still like to cache the cpb_capable value locally instead of getting
> > x86_cpuinfo percpu var and querying it. Especially if this happens often
> > and not only at driver init.
> 
> If it's a percpu var, isn't it local anyway?

I meant driver-local. So that I don't have to deref even the per_cpu var
and thus save some cycles.

-- 
Regards/Gruss,
Boris.

--
Advanced Micro Devices, Inc.
Operating Systems Research Center
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