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

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Message-ID: <20110420131442.GA29418@atrey.karlin.mff.cuni.cz>
Date:	Wed, 20 Apr 2011 15:14:42 +0200
From:	Pavel Machek <pavel@....cz>
To:	Len Brown <lenb@...nel.org>, stable@...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>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	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


> > > However, the typical BIOS fails to initialize the MSR,
> > > and the typical Linux distro neglects to invoke x86_energy_perf_policy(8).
> > > 
> > > The result is that some modern hardware is running in hardware default,
> > > which is "performance" mode, rather than the intended design default
> > > of "normal" mode.
> > > 
> > > Initialize the MSR to the "normal" setting during kernel boot.
> > > 
> > > Of course, x86_energy_perf_policy(8) is available to change
> > > the default after boot, should the user have a policy preference.
> > > 
> > > cc: stable@...nel.org
...
> Will it be possible to measure a performance difference between
> "performance" and "normal"?  Yes, it will be possible.

Ok. So... what "serious bug" does this fix? You really need to use cc:
stable less. Tweaking performance/power ratio is _not_ serious bug.


									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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