linux-kernel - Re: [PATCH] x86 intel power: Initialize MSR_IA32_ENERGY_PERF

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Message-ID: <CA+55aFxBkgwBbnqwO7DuizsWiVcULYtPzqr-mYrT6aHmXV0zZw@mail.gmail.com>
Date:	Wed, 13 Jul 2011 13:49:06 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Len Brown <lenb@...nel.org>
Cc:	Ingo Molnar <mingo@...e.hu>, x86@...nel.org,
	linux-pm@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Arjan van de Ven <arjan@...radead.org>
Subject: Re: [PATCH] x86 intel power: Initialize MSR_IA32_ENERGY_PERF_BIAS

Ack. Let's just do this. Ingo?

            Linus

On Wed, Jul 13, 2011 at 1:44 PM, Len Brown <lenb@...nel.org> wrote:
>
>> So how about informing users, how about making it non-silent? An informative
>> printk that also mentions the power configuration tool, etc. This solves the
>> concerns i mentioned.
>
> Something like this?
>
>                rdmsrl(MSR_IA32_ENERGY_PERF_BIAS, epb);
>                if ((epb & 0xF) == 0) {
>                        printk_once(KERN_WARN, "x86: updated energy_perf_bias"
>                                " to 'normal' from 'performance'\n"
>                                "You can view and update epb via utility,"
>                                " such as x86_energy_perf_policy(8)\n");
>                        epb = (epb & ~0xF) | ENERGY_PERF_BIAS_NORMAL;
>                        wrmsrl(MSR_IA32_ENERGY_PERF_BIAS, epb);
>                }
>
>
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