changing C-state governor

Question

I learnt that we can change P-state governors with the command echo "ondemand" > /sys/devices/system/cpu/cpu0/cpufreq/current_governor

How dooes one change the C state governor ?

Answer 1

I don't believe that you can govern the C state from the OS.

If the CPU supports it, then it will enter lower powered states automatically, BIOS permitting.

But it doesn't make so much sense applying a governor to it in the same way that you control how P states ramp up and down depending on active usage.

Answer 2

Check out this article on C,P, and T-states for power/cpu frequency scaling management.

The long and short of it is from the article is

* cd /sys/devices/system/cpu
* ls -L
* cd cpux/cpufreq
* cat scaling_available_frequencies
* echo -n xxxxx > scaling_max_freq
* echo -n yyyyy > scaling_min_freq

http://greentechnologyinsights.blogspot.com/2009/02/processor-power-management-in-linux.html

Answer 3

it can be changed by going into /sys/devices/system/cpu/cpuidle directory and changing the file scaling_governor from ladder to menu (say)