CPU Frequency Scaling (post 2-16)

Today I've released 2.15.92 which is the last test release before 2.16.0 is released. I'm amazed at the work people have done in the last few weeks to make gnome-power-manager ready for the 2.16.0 release.
Now I've been banned (thanks to the string freeze) making large changes and adding functionality, I've been thinking about functionality to add post 2-16.
I get an email or bugzilla every few weeks asking about CPU frequency scaling, and how to add support into g-p-m. Traditionally the CPU frequency has been changed by system daemons such as cpufreqd (there are a lot more to choose from) which require editing odd files in /etc and are not new-user friendly. Holger Macht has written a addon to control this using HAL, so system and session software can control CPU frequency scaling in an easy, and architecture neutral way.

Maybe this is too much detail for the average user, but the feedback I've been getting is that users are screaming for cpufreq support in g-p-m.
The question is how to expose the options, given that there is are a large number of permutations of governers and working options for any given laptop.
My initial reaction was to hide the “use low power mode” checkbox to do scaling, but some computers scale better than others, and some just dont work in some modes, but do others. So it's got to be exposed in the UI.

So far, all the possible options (assuming you have all the governers installed) are:

#define CPUFREQ_ONDEMAND_TEXT           _(“Based on processor load”)
#define CPUFREQ_CONSERVATIVE_TEXT       _(“Automatic power saving”)
#define CPUFREQ_POWERSAVE_TEXT          _(“Maximum power saving”)
#define CPUFREQ_USERSPACE_TEXT          _(“Custom”)
#define CPUFREQ_PERFORMANCE_TEXT        _(“Maximum performance”)
#define CPUFREQ_NOTHING_TEXT            _(“Do nothing”)

With “Computer processor policy:” as the prefix. New names and descriptions

Tell me what you think.

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Richard has over 10 years of experience developing open source software. He is the maintainer of GNOME Software, PackageKit, GNOME Packagekit, GNOME Power Manager, GNOME Color Manager, colord, and UPower and also contributes to many other projects and opensource standards. Richard has three main areas of interest on the free desktop, color management, package management, and power management. Richard graduated a few years ago from the University of Surrey with a Masters in Electronics Engineering. He now works for Red Hat in the desktop group, and also manages a company selling open source calibration equipment. Richard's outside interests include taking photos and eating good food.

One thought on “CPU Frequency Scaling (post 2-16)”

  1. The user friendly descriptions of “Based on processor load” and “Automatic power saving” are a bit ambiguous to me. They read like they are almost the same thing to me, not sure how I'd pick a policy based on it. After reading the descriptions of on demand and conservative, I'm not sure how I'd condense them down to a few words.

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