Re: kernel module options for cpufreq

[Matthew Garrett <mjg59 srcf ucam org>]

On Mon, Jun 30, 2008 at 09:10:28AM +0200, Adam Tkac wrote:
> On Fri, Jun 27, 2008 at 05:13:24PM +0100, Richard Hughes wrote:
> > * remove CONFIG_CPU_FREQ_GOV_POWERSAVE -- ondemand automatically
> > throttles down to lowest, and is just a hardcoded state
> 
> I don't think removal of powersave governor is good idea. Generally
> ondemand governor does great job but in some cases doesn't. For
> example when I play some films in mplayer ondemand sets frequency to
> max which is not needed, of course.

The same can be achieved by altering 
/sys/devices/system/cpu/*/cpufreq/scaling_max_freq, but it's still 
likely that you're consuming less power when ondemand is setting your 
frequency to max. An idle fast processor consumes less power than an 
active slow one.

> Powersave governor is also good in case that you have bad fan in your
> laptop and you are going to compile some big source. Without powersave
> it is not possible (yes, it really happens :) )

http://lkml.org/lkml/2008/6/16/100

> I think we should preserve ondemand and powersave governors (and
> potentialy others as Dave Jones wrote in this thread). Please don't
> drop them in favour of your project which might be generally better but
> I believe there are cases where current governors are better.

I'm open to indications as to what these are :) Powersave is 
semantically identical to ondemand with scaling_max_freq altered. 
Performance is semantically identical to ondemand with scaling_min_freq 
altered. 

-- 
Matthew Garrett | mjg59 srcf ucam org