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Experiment change in frequency

lyf sci
Genius 3720 points

Hi Experts,

I am using AM335x starter kit EVM. Let us assume I had configured frequency governor with to increase frequency on load increases.

How to experiment the change in frequency of processor when the processor load increases ? Something like reading the respective PLL registers from user space or ticks per second ?

  • 0
    Guru 20755 points

    Hi,

    You can first check to see if it is changed in linux:

    $ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq

    125000

    $ cat /proc/cpuinfo

    Processor  : ARMv7 Processor rev 3 (v7l)

    BogoMIPS  : 125

     

    Thanks

    Ran

  • 0 in reply to ranchu
    TI__Expert 4475 points

    Hi,

    View also all available governors:
    root@am335x-evm# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
        ondemand userspace performance conservative powersave
    View current governor:    
     root@am335x-evm # cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor         ondemand
    View and Change Frequency (OPP):
    First, set cpufreq governor to userspace
    View current frequency:
    root@am335x-evm# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
    720000
    View current voltage:
    root@am335x-evm# cat /sys/class/regulator/regulator.3/microvolts
    1262500
    View Supported OPPs:
    root@am335x-evm# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
    275000 500000 600000 720000
    Change Frequency to 500MHz:
    root@am335x-evm# echo 500000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed

    BR

    Ivan

  • 0 in reply to Ivan Matrakov
    Genius 3720 points

    Hi Ivan,

    Thanks for the reply.

    I understand the power management option.

    Say I had configured the ondemand then how I could see the change in frequency if the processor load increases ?

  • 0 in reply to lyf sci
    TI__Guru** 116100 points

    Hi Lyf,

    You need to refer to the Linux CPUFreq framework document.

    Documentation\cpu-freq

    If you have configured as "ondemand", the frequency would configured to high when CPU loaded much and frequency would reduced when CPU loaded less.