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PROCESSOR-SDK-DRA7X: Does TI has any userspace tool for userspace governer

Pradeep G
Intellectual 450 points

Part Number: PROCESSOR-SDK-DRA7X

Hi, 

This is related to dynamic CPU frequency scaling for DRA75x processor.

Does TI provide/recomment any userspace test application for userspace governor which can handle freq scaling based on CPU load which can be tuned based on requirements.

  • 0
    TI__Mastermind 42515 points
    Hi Pradeep,

    the Linux kernel supports Dynamic Voltage and Frequency scaling (DVFS), please check this documents:
    processors.wiki.ti.com/index.php
    processors.wiki.ti.com/.../GLSDK_DRA7xx_PM_DVFS_User_Guide

    Regards,
    Yordan
  • 0 in reply to Yordan Kamenov
    Intellectual 450 points
    Yes, I have already checked these.
    What I am looking for is how to ensure the POH criteria for SOC with a userspace governor ?
    Is there any opensource userspace governor that TI recommends which can ensure we satisfy POH for SOC
    OR if 'ondemand' or 'conservative' governor is used, does it automatically ensure POH ?

    Any insights here would be very helpful
  • 0 in reply to Pradeep G
    TI__Expert 8250 points

    Pradeep

    Userpsace governor is a standard linux feature and allows you to explicitly set the operating point from SW

    I am assuming the POH rating is defined for a particular operating point

    If you use ondemand governors, it would be difficult to estimate the amount of time spent in each operating point.

    Performance governor would operate the system at the highest possible operating point all the time.

    You can choose the appropriate governor based on your use case requirement

  • 0 in reply to Pradeep G
    TI__Genius 13567 points

    The SDK supports CPUFreq for the Arm processors. To change the frequency of GPU, DSP, and IVA that is done through options in the u-boot defconfig file. See this page on how to use CPUFreq. First you must set the governor to "userspace" then echo the desired frequency in Hz to /sys/bus/cpu/devices/cpu0/cpufreq/scaling_setspeed.

  • 0 in reply to Srirama Govindarajan
    Intellectual 450 points

    Thanks for feedback

    What I am looking for is as below.

    1. TI defines a set of OPP supported for a SOC.

    2. TI defines a set of POH for a SOC based on OPP  used either constant or a ratio of different OPP's

    3. TI SDK provides option of freq scaling 

    Now, to use frequency scaling, I want to understand if the available governors (ondemand or conservative) can ensure ratio of OPP to meet the POH criteria or can they be fine tuned

    OR is there any opensource application that uses userspace governor that can be fine tuned to meet ratio of OPP to in turn meet the POH.

  • 0 in reply to Pradeep G
    TI__Expert 8250 points
    Pradeep

    POH is a function of voltage and temperature . The device datasheet describes the duty cycle assumed for the rated POH i.e. it specifies the POH as a function of junction temperature . As an illustration for POH of 2000 Hrs it is assumed that the device is operated 5% time @ -45c, 65%@70c, 20%@110c, 10% @125c

    Similarly POH is specified as function of Voltege/frequency(duty cycle of operating points).

    Linux Governor for CPUFREQ allow operating the system at a specified operating point dynamically (ondemand governor) or statically(userpsace, performance). Hence the means to effect a change in OPP is there - but we do not have a policy, higher level framework that can map this back to POH for the device.

    Assuming that you choose Userspace governor, the logic to count the amount of time spent in particular OPP and change between OPP needs to be implemented separately on top - not aware of specific solutions towards these.
  • 0 in reply to Srirama Govindarajan
    Intellectual 450 points
    The logic you mentioned is exactly what i was searching for, if anything can be reused :)
    Thank you, will take it from here.
  • 0 in reply to Pradeep G
    TI__Expert 8250 points
    Pradeep
    Will mark the issue as resolved for now