6 Replies Latest reply on Sep 19, 2015 12:15 PM by Aditya_Bansal

    CPU frequency ondemand

    rosenrot

      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

        • 1. Re: CPU frequency ondemand
          Intel_Peter

          Hello rosenrot,

           

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

           

          Regards,

                      Peter

          • 2. Re: CPU frequency ondemand
            Intel_Peter

            Hello rosenrot,

             

            Here's what I could find out about the subject, this 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

            • 3. Re: CPU frequency ondemand
              rosenrot

              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

              • 4. Re: CPU frequency ondemand
                rosenrot

                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 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.

                • 5. Re: CPU frequency ondemand
                  rosenrot

                  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.

                  • 6. Re: CPU frequency ondemand
                    Aditya_Bansal

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