Home Wiki > Talk:Powersaving
Sign up | Login

Talk:Powersaving

tagline: From openSUSE

Reduce Laptop APM Loadcycle

HowTo Save Your Laptop Hard Disk From Linux-"The Exterminator"

http://old-en.opensuse.org/Reduce_laptop_APM_loadcycle

Use Default Kernel

Some users reported better performance with the default kernel instead of the desktop kernel. Even if the reasons are not known yet, it might be worth a try.

Disk Power Management

Because bad things can happen when your power-management disk parks or spins down too often, you may want to use the following scripts to manage the situation a little better.

http://old-en.opensuse.org/Disk_Power_Management

General Guide on how to Reduce Power Consumption

http://www.thinkwiki.org/wiki/How_to_reduce_power_consumption

Effect of Voltage Scaling in SpeedStep Technology and CPU Policy

In the section titled "Why is there no GUI for changing the CPU Policy (CPU governors)?", there is a fallacy regarding the use of the "powersave" CPU policy setting. The section states that cpu-intensive tasks will take proportionally longer when the cpu speed is lower, and hence the total energy consumed to complete the task will be the same. While it is true that a cpu-intensive task will take proportionally longer with a slower clock, the total energy consumed may in fact not be the same. This is because many versions of SpeedStep technology also adjust the CPU core voltage when the speed is adjusted. Because power in CMOS technology is proportional to both the frequency and the square of the voltage (P ~ C*V^2*F), this voltage reduction has a significant effect on the power, and hence the total energy used. When the CPU voltage is lowered along with the frequency, a task will consume less energy even though it takes proportionally longer.

The difference in energy consumed may not be significant in a desktop environment, where "ondemand" is probably the best setting all of the time, but for a laptop on battery it can make a difference depending on usage patterns. Because of this, there should be a place in the power management GUI to allow the CPU policy of "powersave" while on battery, as there were in past versions of openSUSE.