how to set cpu powermanagement function in powerprofiles?

English Hardware
#1

i cant seem to find the setting for cpu powermanagement function in the powermanagement profiles.
in 11.3 / kde 4.3 one could set the cpu powermanagement function on / off. this resulted in significant power consumption change and performance change.
does anyone know how to do this in 11.4 / kde 4.6?

#2

Are you referring to dynamic freqency scaling of the cpu (cpu throttling)? If so, it should be on by default, assuming your cpu supports it. Yes, KDE 4.6 isn’t involved in setting that. Take a look in YaST.

You can use the command cpufreq-info in terminal (normal user) to display the settings. Check that the package “cpufrequtils” is installed on your system.

#3

Where exactly in Yast can I find it?

This is really annoying, KDE behaves like Gnome - removing features and options not to confuse users… In KDE 4.5 it was possible to control the frequency by some ???-solid-??? command, in KDE 4.6 it got lost. So my temporary workaround is using kdesu and cpufreq, but I am not happy about need to input root’s password every time I disconnect from the electricity…

#4

Controlling the frequency of the processor(s) is not a feature I would normally expect to be done by a Desktop Environment. It clearly belongs with the linux operating system. The function is common to, but independent from KDE, Gnome or whatever DE is running, and even when no DE is running the processor(s) need to be governed.

Using cpufreq-info, you can see which cpufreq governor is operating, and normally it’s the “ondemand” governor that is the default where frequency increases, as and when applications demand more processing power. When the demand falls so does the frquency, and so does the power consumption. That assumes your cpu supports it (throttling), and most processors do (certainly over the last five years).

It has nothing to do with switching from mains to battery power. I run with “ondemand” in both situations i.e. the system is in charge of cpu power saving.

So my temporary workaround is using kdesu and cpufreq, but I am not happy about need to input root’s password every time I disconnect from the electricity…

For what reason?

#5

Well, I was used to that KPowerdevil takes care of it. It worked great for me. I know, what ondemand means, but on my hardware with ondemand I get much less time than with powersave. Maybe less power, but more time - and that’s important for me.

For what reason?

Because I want powersave on battery and ondemand when in electricity. And I haven’t found any other workaround.

…
So if not Kpowerdevil, what is the way to auto set the frequency?

#6

You can try installing the package “yast2-power-management” from 11.4’s Oss repo. Then you can go Yast>System>Power Management to set it up. You should get “powersaving” and other profiles. You can then select a profile as appropriate.

However, that may not be any easier/quicker than using the cpufreq-set command from a terminal even though root access is required, e.g to change governor to powersave:

cpufreq-set -g powersave

For more detail see the “cpufreq-set” man page. Is that the cpufreq utility you are currently using as your “workaround”?

#7

You can try installing the package “yast2-power-management” from 11.4’s Oss repo. Then you can go Yast>System>Power Management to set it up. You should get “powersaving” and other profiles. You can then select a profile as appropriate.

This gives some error “cannot restart daemon pm-profiler”, I looked for the services running - pm-profiler wasn’t enabled and enabling it would also mean enabling HAL daemon…

Is that the cpufreq utility you are currently using as your “workaround”?

Yes, I had something like

kdesu -c "cpufreq-set -g powersave"/CODE] added as a script in kpowerdevil setup.

But I've just installed "laptop-mode-tools", so I will see, if there is some possibility to set automatic switching between powersave and ondemand.
#8

But I’ve just installed “laptop-mode-tools”, so I will see, if there is some possibility to set automatic switching between powersave and ondemand.

What a coincidence. I was just re-reading some stuff on the internet about my notebook (by an Arch user), and noticed the following statement:

Laptop-mode-tools is a laptop power saving package for Linux systems (a shell script and a bunch of config files really). I configured acpid to call it when I switch to/from battery power. It can enable the Laptop Mode feature of the kernel, control CPU throttling …

That may give you a clue, but I couldn’t see any more info on how “acpid” was configured.