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CPU frequency ondemand

MMich22
New Contributor II
1,598 Views

I was wondering if it is possible to adjust the CPU speed ondemand. I installed cpufrequtils and it tells me that the lower and higher limit are both 500MHz.

Wouldn't it be nice to be able to slow the CPU speed down to about 100MHz? Is this possible or is there a reason not to do so?`

I'm running ubilinux by the way.

Cheers

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6 Replies
Pedro_M_Intel
Employee
197 Views

Hello rosenrot,

We will investigate and as soon as get get some usefull info I will reply you back.

Regards,

Peter

Pedro_M_Intel
Employee
197 Views

Hello rosenrot,

Here's what I could find out about the subject, this http://www.thinkwiki.org/wiki/How_to_use_cpufrequtils link is a little manual to use cpufrequtils, it should help you modify the CPU frequency as you want. If you have any more doubts, don't hesitate to ask.

Regards,

Peter

MMich22
New Contributor II
197 Views

Hello Peter,

thanks a lot for your answer. I have some questions about the parameters. The maximum frequency is clear, it is 500MHz. Is there a limit for the minimum frequency or do you have proposed values for the steps (ie. 50,100,200,300,400,500 MHz)?

I will try to adjust those values and let you know if I run into problems.

Cheers,

rose

MMich22
New Contributor II
197 Views

I tried to change the cpu frequency but it did not work.

Ondemand:

cpufreq-set -d 100MHz -u 500MHz -g ondemand

Userspace:

cpufreq-set -f 100MHz

/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq is set to 500MHz. Therefore cpufrequtils does not change anything.

I tried to edit this file but I do not have write permission, also I do not know if this would harm my edison.

root@ubilinux:~# cpufreq-info

cpufrequtils 008: cpufreq-info (C) Dominik Brodowski 2004-2009

Report errors and bugs to mailto:cpufreq@vger.kernel.org cpufreq@vger.kernel.org, please.

analyzing CPU 0:

driver: sfi-cpufreq

CPUs which run at the same hardware frequency: 0

CPUs which need to have their frequency coordinated by software: 0

maximum transition latency: 100.0 us.

hardware limits: 500 MHz - 500 MHz

available frequency steps: 500 MHz

available cpufreq governors: ondemand, userspace, performance

current policy: frequency should be within 500 MHz and 500 MHz.

The governor "userspace" may decide which speed to use

within this range.

current CPU frequency is 500 MHz (asserted by call to hardware).

cpufreq stats: 500 MHz:100.00%

analyzing CPU 1:

driver: sfi-cpufreq

CPUs which run at the same hardware frequency: 1

CPUs which need to have their frequency coordinated by software: 1

maximum transition latency: 100.0 us.

hardware limits: 500 MHz - 500 MHz

available frequency steps: 500 MHz

available cpufreq governors: ondemand, userspace, performance

current policy: frequency should be within 500 MHz and 500 MHz.

The governor "ondemand" may decide which speed to use

within this range.

current CPU frequency is 500 MHz (asserted by call to hardware).

cpufreq stats: 500 MHz:100.00%

Help is welcome.

MMich22
New Contributor II
197 Views

I'm a little bit frustrated that after 6 months there is still now answer to my "easy" question. Please give some feedback if you want the Intel Edison to be a leading development platform. If one thing is important for an development board, it is the community behind it.

ABans1
New Contributor I
197 Views

@Intel_Peter -- 4 more months. Any info on how to change the CPU frequency?

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