powertop is getting it wrong… – Technical Blog of Richard Hughes

The powertop utility from INTEL has been very interesting to use. Unfortunately, I'm quite pissed off.

“gnome-power-manager doesn't dim the backlight to save power it actually just changes the colour of the pixels on the screen”

Err no. It never has and never will. It actually dims the backlight on all the hardware I have tested it on.

Dimming to 30% when idle saves me about 1-3W of power on all three laptops I own. That's a X60 (ibm+intel), n100 (lenovo+nvidia) and a A10 (toshiba+old-intel).

For the X60, g-p-m calls HAL, which writes to the thinkpad_acpi controlled backlight class. This then writes a value into the embedded controller address space (or issues a CMOS command) which changes the hardware backlight brightness.

Really impressive graph by the way – but what crack are you smoking?

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hughsie

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. View all posts by hughsie

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hughsie

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