Some people have different views by saying that it’s not entirely up to the Kernel of an OS to enhance the power management features. It maybe true to some extent, but still, since the Kernel is the software that communicates directly with your hardware, the Kernel has a major role to play nonetheless.
Also because almost all the computer manufactures make sure their hardware are optimized/compatible with MS Windows platform and as a result a Laptop, Netbook or any mobile device might always get a better battery life under Windows than while running any other OS.
For instance, I had a netbook recently and under Ubuntu 11.04 Natty Narwhal the CPU fan was always running in somewhat decent speed. Apart from the “unnecessary” power consumptions it was also a bit annoying because of the high pitch sound that it made.
That netbook originally came with Windows 7 and under Windows the fan wasn’t running all the time. So clearly it’s either the fault of the Kernel or a “buggy” system service or any other app that runs on top of that OS.
That’s not to say GNU/Linux suck when it comes to mobile computing. Far from it actually because we have manufactures like Dell for instance who’s known to manufacture computers that are extremely compatible with GNU/Linux (they’ve even written few tools of their own so you can tweak power management settings with ease as well).
But the point is, when comparing with Windows GNU/Linux hasn’t been doing that well while efficiently managing the power usage.
But Ubuntu Kernel developer called “Colin” has started a project hoping to address some of those power management issues for the upcoming Ubuntu 12.04 LTS release.
Colin has written a blog post concerning various ways to improve the power management features in Ubuntu 12.04 and prior to that, he has tested power consumptions under various scenarios using a “6.5 digit precision multimeter” for answering some common issues/questions such as:
*. The accuracy of “PowerTop” (a tool for GNU/Linux for observing apps that are “misbehaving” while the computer is at its “idle” states).
*. Accuracy of “ACPI” readings.
*. General Backlight power usage of Laptops.
*. Main reasons behind HDD wake-ups.
*. Consider re-enabling “Aggressive Link Power Management” (ALPM: a technique used for putting devices that uses the SATA into a low power modes).
*. What system services are behind common HDD wake-ups.
*. Accuracy of the power.d scripts.
*. Considering enabling a PCIe ASPM “fix” … are again some of his questions to mention
He also says that …
“… PowerTop analysis has shown we can save another 1-2 Watts of power by putting USB and PCI controllers of devices like Webcams, SD card controllers, Wireless, Ethernet and Bluetooth into a lower power state…”
A “Watt” or “Two” may not sound much but in truth it can have a big impact for the overall battery life.
To see whether these suggestions can make a difference or not, they first need “mass” testing and using this Ubuntu Kernel power management Wiki page we can contribute to this project which will be beneficial for all of us in the long term I suppose.
Once inside of that page you’ll be given an extremely simple steps (won’t take more than few minutes) for giving Kernel developers your PC’s current power usage etc for their testings (you just gotta run a script and the rest is pretty much automatic).
You can read more about it from this blog post written by Colin. Good luck.