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Thread: How do I enable Windows 7 style power profiles in OpenSuse?

  1. #1

    Question How do I enable Windows 7 style power profiles in OpenSuse?

    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?



    Thank you.

  2. #2

    Default Re: How do I enable Windows 7 style power profiles in OpenSuse?

    In the Energy Savings options in System settings there are different tabs one for plugged in and one for on Battery. For the on battery you could choose run script option and create a script to reduce CPU frequency?

  3. #3

    Default Re: How do I enable Windows 7 style power profiles in OpenSuse?

    Quote Originally Posted by kevtongue View Post
    In the Energy Savings options in System settings there are different tabs one for plugged in and one for on Battery. For the on battery you could choose run script option and create a script to reduce CPU frequency?
    Hi kev,
    Sorry about the late reply, was on an official trip.
    To be honest, I am using openSuse 13.2 on my i7 laptop. Just started downloading openSuse Leap 42.3


    I will install it on a cheap notebook and experiment on it first before I start using it on my main laptop.

    Came across an interesting article here: https://doc.opensuse.org/documentati...ing.power.html
    Looks like the problem of dynamic frequency while on battery can be solved by using something called cpupower.

    Unfortunately, I'm neither a programmer nor a Linux pro, I have no clue how to write scripts- are they like DOS .bat files?
    Anyway, would it be possible for you (or someone else) to help me set a static frequency (the lowest possible) for this test laptop which will soon be running 42.3? I don't want to type in commands every time I unplug/plug the AC cable, it'd be great if I could configure the system to do this switching automatically- use adaptive frequency when on AC, switch to lowest available frequency when unplugged.

    Thank you for taking the time to post a reply, and once again sorry for the late response- i didn't abandon the thread, just got caught up in work..

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