I used to work on my laptop on
ondemand governor, which was switching CPU frequency depending on CPU usage. It worked quite nice for years and had three very important advantages:
- low hardware temperatures
- quiet fan
- high performance when needed
Now I've upgraded both my laptop (to Lenovo B5400, Intel Pentium 3550M) and system (Ubuntu 14.10) and I've found that:
powersavegovernors are available;
ondemandis no longer available and supported
- something has been changed in setting files, because current governor and min/max speeds are restored to defaults every time I boot up
In consequence my system:
- still turns governor back to
performance, which is wrong, I believe
- whatever governor is, cpufreq-info tells me that "frequency should be within 2.30 MHz and 2.30 GHz" although available frequencies starts from 800MHz
I've tried to edit
/etc/init.d/cpufrequtils defining the following setting:
I've also tried to edit
scaling_min_freq file in
/sys/devices/system/cpu/cpu0/cpufreq and set it to 800000.
And, guess what, after restarting system I'm again in
performance mode with frequency "scaled between" 2.30GHz and 2.30GHz.
Could you, please, explain me:
a) where exactly in Ubuntu 14.10 are a master settings of min/max CPU frequencies?
b) how to define frequencies and governors to achieve the same result as old good
ondemand? (I would like to work on the lowest frequency possible and go up only on heavy load)
c) and how to avoid resetting what I defined, of course.
I'd be grateful for explanations.