Messages in this thread | | | Date | Fri, 5 Mar 2010 21:40:29 +0100 | From | Pavel Machek <> | Subject | Re: [patch 2/2] x86: Manage ENERGY_PERF_BIAS based on cpufreq governor |
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Hi!
> >You should say what the setting does; you can mention below what MSR > >it corresponds to, but "Control IA32_ENERGY_PERF_BIAS setting" is not > >suitable user documentation. > > > >> Also, the expectation here is that kernel will do the right thing by > >> default. The option here is to the user who_knows_what_he_is_doing to > >> override the kernel default. > > > >You did not give user enough information to do anything intelligent... > > I have rephrased it in the newer version sent yday with more info.
Good.
> >> > Also... does it make change to tweak the setting during > >runtime? Maybe > >> > different settings for AC and battery power? > >> > >> Yes. Matthew mentioned in other response aboue setting this based on > >> freq. For the CPUs that support this feature currently, we don't see > >> advantage in setting this feature at run time. > > > >If the feature is useless, then why set it at all? > > I just said changing it at run time doesn't give us benefits. Not >that
That can be only true if it does not give benefits period... AC and battery power are quite different scenarios.
> the feature is useless. Having the default value for the tunable in > mid-range does increase energy-efficiency than the tunable being > at performance level.
So... what does it really do? What is the difference in power consumption, and what is the difference in performance? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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