How to properly switch between cpupower governors?

[duffman128]

Hi there. I'm new to linux and the forum. I have to say that I'm loving gnome 3 and fedora 16 so far.

I have a few problems though with fedora 16. One of them is switching between cpu frequency governors. Whenever I try to switch a governor using "sudo cpupower frequency-set -g <governor>", the program seems to save the current frequencies to <governor>

Here's an example:
[user@local ~]$ cpupower frequency-info
analyzing CPU 0:
driver: acpi-cpufreq
CPUs which run at the same hardware frequency: 0 1
CPUs which need to have their frequency coordinated by software: 0
maximum transition latency: 10.0 us.
hardware limits: 1.20 GHz - 2.50 GHz
available frequency steps: 2.50 GHz, 2.00 GHz, 1.60 GHz, 1.20 GHz
available cpufreq governors: conservative, userspace, powersave, ondemand, performance
current policy: frequency should be within 1.20 GHz and 2.50 GHz.
The governor "ondemand" may decide which speed to use
within this range.
current CPU frequency is 1.20 GHz.
boost state support:
Supported: yes
Active: yes
[user@local ~]$ sudo cpupower frequency-set -g powersave
Setting cpu: 0
Setting cpu: 1
[user@local ~]$ cpupower frequency-info
analyzing CPU 0:
driver: acpi-cpufreq
CPUs which run at the same hardware frequency: 0 1
CPUs which need to have their frequency coordinated by software: 0
maximum transition latency: 10.0 us.
hardware limits: 1.20 GHz - 2.50 GHz
available frequency steps: 2.50 GHz, 2.00 GHz, 1.60 GHz, 1.20 GHz
available cpufreq governors: conservative, userspace, powersave, ondemand, performance
current policy: frequency should be within 1.20 GHz and 2.50 GHz.
The governor "powersave" may decide which speed to use
within this range.
current CPU frequency is 1.20 GHz.
boost state support:
Supported: yes
Active: yes
[user@local ~]$

My question is how do I properly switch between the governors?

[Speeddymon]

I realize this thread is old; it came up after I posted a similar but unrelated thread, and I saw there was no answer. It appears you are doing it the right way. What seems to be happening is that your ondemand governor is already running at the lowest available speed:

ONDEMAND
[user@local ~]$ cpupower frequency-info
-snip-
hardware limits: 1.20 GHz - 2.50 GHz
available frequency steps: 2.50 GHz, 2.00 GHz, 1.60 GHz, 1.20 GHz
available cpufreq governors: conservative, userspace, powersave, ondemand, performance
current policy: frequency should be within 1.20 GHz and 2.50 GHz.
The governor "ondemand" may decide which speed to use
within this range.
current CPU frequency is 1.20 GHz.
-snip-

POWERSAVE
[user@local ~]$ cpupower frequency-info
-snip-
hardware limits: 1.20 GHz - 2.50 GHz
available frequency steps: 2.50 GHz, 2.00 GHz, 1.60 GHz, 1.20 GHz
available cpufreq governors: conservative, userspace, powersave, ondemand, performance
current policy: frequency should be within 1.20 GHz and 2.50 GHz.
The governor "powersave" may decide which speed to use
within this range.
current CPU frequency is 1.20 GHz.
-snip-

The BOLDED items above indicate that your CPU supports a minimum frequency of 1.2GHz and a max of 2.5GHz. If your system were under load, then while the ONDEMAND governor was active, the frequency should be higher. In other words, the ondemand governor provides the higher frequency when the system requests it, but otherwise provides the lower frequency -- there's no reason for the system to run at 2.5GHz when it is otherwise idle.

On the other hand, the POWERSAVE governor will be more conservative about raising the frequency, and therefore will keep it at the lower end even if the system requests it, only raising it when absolutely necessary.

Based on that, I believe it is working as expected.