linux-kernel - Re: [PATCH 2/5] acpi-cpufreq: Add support for disabling dynamic overclocking

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Message-ID: <20110802205044.GA21330@aftab>
Date:	Tue, 2 Aug 2011 22:50:44 +0200
From:	Borislav Petkov <bp@...64.org>
To:	Len Brown <lenb@...nel.org>
Cc:	Matthew Garrett <mjg@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"davej@...hat.com" <davej@...hat.com>,
	"Langsdorf, Mark" <mark.langsdorf@....com>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>
Subject: Re: [PATCH 2/5] acpi-cpufreq: Add support for disabling dynamic
 overclocking

On Tue, Aug 02, 2011 at 04:21:16PM -0400, Len Brown wrote:
> While this patch will work and is not invalid, I don't like it.
> 
> It advertises a user I/F that suggests that disabling turbo
> is on a per logical processor basis -- but a write to
> any of the attributes will write to every CPU in the system.
> 
> Either it should do per-cpu limiting (which, btw doesn't
> work if you use the MISC_ENABLES MSR method in this patch,
> and would instead need to use the PERF_CTL.32 method)
> or there should be a per-system attribute
> that reflects that this knob is per-system.

Agreed with the per-system thing. The reason to disable boosting on
all cores is very simple: nobody has come up with a usecase until now
which needs disabling only a subset of the cores. Also, this way the
implementation is the simplest.

-- 
Regards/Gruss,
Boris.

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