This might be a duplicate thread, my apologies if it is.
A google search pointed me to this article which says reducing CPU frequency doesn’t result in power saving- consequently it’s unavailable in OpenSuse.
I humbly disagree.
While the logic given in that article is sound in theory, in real life reducing CPU frequency does make a difference.
Intel’s Enhanced SpeedStep doesn’t just reduce the clock rate, but reduces the power consumption of the CPU when it’s running at a slower clock.
I have real life data to support my claim. In Windows, when I am using the power saver profile, my laptop plays videos in VLC for 5.5 hours before showing “Low Battery”. In openSuse, the same laptop playing the same video in VLC complains about low battery after about 2.5 hours.
Turns out that the laptop is clocking the CPU at 2.0 to 2.5 GHz while playing the video, resulting in the cooling fan powering up and spinning, which results in additional power consumption. Windows has similar behavior if “Balanced” power profile is selected. But in power saver mode, Windows is running the CPU at 0.77GHz, and the cooling fan is powered down (not spinning). The logic given in the opensuse article against CPU frequency reduction doesn’t work in this case, the CPU cannot the clocked to full speed for a little while and then switched to idle- it must keep running as long as the laptop is playing the video, and it keeps running constantly at a high frequency.
So there we go, I need a way to enable power saving, specifically- CPU frequency reduction, while running on battery power.
Ideally, I would like to use the normal OpenSuse power management scheme when working on AC (The CPU is Core i7 5500U, my laptop can turbo boost to 3.0 GHz and I don’t mind it running at full speed when plugged in), and switch to the lowest possible CPU frequency the moment AC power is lost (This is 0.77GHz in my case), and I would like OpenSuse to do this AUTOMATICALLY for me.
Can this be done?
https://s14.postimg.org/5wtfwvde9/Capture.jpg
Thank you.
