cpufreq directory not present. How to change governor for P states in such a case

kashyapa · 10-27-2009, 08:28 PM

One node in my cluster is using ondemand governor which is specified in the directory
/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor ..
Scaling_governor allows us to choose the governor of our choice .
But this sub-directory is absent in the other node of the cluster . How do I change the governor for Pstates in such case ?

clvic · 10-29-2009, 01:53 PM

Is your system a real SMP system (two processors), or a dual core system?
In most dual core systems, the governor and the frequency must be the same on both cores - I think that's why you only see one entry for governor.
On my system, and AMD Athlon X2, dual core, I see the governor entry for both CPUs, but if I change one governor, the other one changes as well.

kashyapa · 10-29-2009, 02:06 PM

Quote:

Originally Posted by clvic

Is your system a real SMP system (two processors), or a dual core system?
In most dual core systems, the governor and the frequency must be the same on both cores - I think that's why you only see one entry for governor.
On my system, and AMD Athlon X2, dual core, I see the governor entry for both CPUs, but if I change one governor, the other one changes as well.

It is two dual core thinkpads forming the two nodes of the cluster

clvic · 10-31-2009, 06:43 PM

Are the two nodes identical? Same CPU?
If yes, look at the installed modules (lsmod). In case, try using "modprobe" to load the right modules.
For instance: "modprobe acpi_cpufreq" should load a module to change cpu frequency for most processors (I think this is a generic module, some processors will work better with a specialized module such as powernow-k8 in my ATHLON system).
To load the governors, you should load at least one of this modules: "cpufreq_conservative", "cpufreq_powersave", "cpufreq_userspace"

kashyapa · 11-03-2009, 08:24 AM

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

How does one change the C state governor ?

kashyapa · 11-03-2009, 08:53 AM

what is the difference between a C-state governor and P-state governor ?
What I have understood is this.. C-state governor are ladder and menu governors which are used during cpuidle states... and P-state governors are Ondemand, conservative, userspace, powersave, performance.... these are used when cpu is working (not idle)

Is my understanding correct ? Also I would like to know how to change current C-state governors from ladder to menu governor .

TB0ne · 11-03-2009, 11:51 AM

Quote:

Originally Posted by kashyapa

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

How does one change the C state governor ?

Don't double-post the same question....this is the same one you posted in your other thread.

GrapefruiTgirl · 11-03-2009, 02:58 PM

Kashyapa:

I have merged your two threads here that were in "Linux Server" as they are nearly identical. Also, consider this post a verbal warning-- I'm asking you to NOT post the identical, or nearly identical, question in multiple places, as this makes it difficult for people to help you and to follow your issue. Please think your question through, and post it in one location only.

Kind regards,

Sasha