Re: [PATCHSET] 0/3 Dynamic cpufreq governor and updates to ACPI P-state driver

[Ducrot Bruno <ducrot@poupinou.org>]

On Thu, Oct 23, 2003 at 10:29:37AM +0200, Arjan van de Ven wrote:
> On Thu, Oct 23, 2003 at 11:24:01AM +0300, Alexander Bokovoy wrote:
> > On Thu, Oct 23, 2003 at 10:19:44AM +0200, Arjan van de Ven wrote:
> > > On Wed, 2003-10-22 at 20:21, Pallipadi, Venkatesh wrote:
> > > 
> > > > And with the kind of power savings that comes with these frequency
> > > > changes, this behaviour 
> > > > results in  longer battery life. However, as yet I do not have any
> > > > numbers to quantify this gain, 
> > > > mainly because I do not have any setup where I can measure actual power.
> > > >  
> > > 
> > > some time ago I did this by using the ACPI method of asking the battery
> > > what the current use is at this point in time; it's of course not as
> > > exact as a full measurement setup but it's a nice poor mans power watch
> > > too ....
> > Unfortunately, there is a number of ACPI-enabled BIOSes which report wrong
> > battery rate when EST is in action -- they still continue to report a rate
> > which corresponds to highest CPU frequency despite the fact that actual
> > frequency might be the lowest one.
> 
> ok I admit to cheating and not actually using ACPI but talking
> to the battery directly based on reverse engineered info (partially based
> on the AML, mostly on "if I do this what value changes" ;)

Most modern embedded chips 'cache' results.  Better to go directly
to the smbus for those one, and talk to the smart battery slave.

-- 
Ducrot Bruno

--  Which is worse:  ignorance or apathy?
--  Don't know.  Don't care.