Is there any command to check the CPU Core Voltage at any point of time on Nvidia Jetson Nano

Power Management for Jetson Nano documentation suggests the CPU Core voltage changes as per the CPU Core frequency change.

We can set the core frequency to any of the supported frequencies by setting the governor to userspace and writing the desired frequency to cpufreq/scaling_setspeed file.

Is there any command that can check the CPU voltage at any point of time to see that the voltage also changing as per frequency change?

hello sarojpanda.blr,

you may enable the tegrastats utility to check the power consumption,
please also refer to Software-Based Power Consumption Modeling for checking details through INA3221 power monitor.
thanks

Thank you @JerryChang for your response. tegrastats utility has a lot of statistics but, I did not find anything specific for CPU core voltage. I am looking for commands similar to the Raspberry Pi utility command β€œvcgencmd measure_volts core”, which gives the CPU core voltage at any instance of time. Do we have any such utility available for Nvidia Jetson Nano?

please check details through INA3221 power monitor, in_voltage*_input. thanks

I am using the Jetson Nano 2GB board.
It seems β€œJetson Nano 2GB does not have an INA3221 power monitor.”

Link: Tegra Linux Driver

Any other tool or way to check the CPU core voltage?

Best Regards,
Panda

hello sarojpanda.blr,

yes, Jetson Nano 2GB does not have an INA3221 power monitor.
since Nano-2GB share the same nvpmodel spec with Jetson-Nano, may I know what’s your actual use-case to check the CPU core voltage?
thanks

Hello JerryChang,

I am conducting some energy consumption experiments using DVFS (Dynamic Voltage and Frequency Scaling) and will possibly be writing a paper on that. I scale the CPU frequency from userspace as per my application requirement. I need to see how the CPU core voltage scales with respect to frequency scaling to justify my results.

Regards,
Panda

hello sarojpanda.blr,

suggest you should work with Nano platforms instead of Nano-2GB.

BTW,
you’ll need to specify regulators if you’re having your driver implementation.
there’re regulators that defined in device tree for driver’s usage. you may look into the nodes, monitor the voltage changes with your use-case,
here’s sysnode for checking all regulators,
for example, /sys/kernel/debug/regulator/regulator_summary.

1 Like

Hello JerryChang,

I do not have any driver implementation. My experiment goal is to use DVFS to save energy in my experiment. I ran a dummy experiment of computing a sum of 1500000 random floating-point numbers. I used the frequencies [β€˜102000’, β€˜307200’, β€˜518400’, β€˜710400’, β€˜921600’, β€˜1132800’, β€˜1326000’, β€˜1479000’] and measured the energy using a power meter. I observed that the energy consumed for each of the frequencies [β€˜102000’, β€˜307200’] to be around 63 milli watt-hours. Similarly the energy consumed for each of the frequencies [β€˜518400’, β€˜710400’, β€˜921600’, β€˜1132800’, β€˜1326000’, β€˜1479000’] remains around 84 milli watt-hours.

Changing only the frequency affects execution time but does not affect the energy consumption of the operation. However, a change in voltage affects energy consumption. From the result above, I believe there are only two voltage levels supported. A low voltage for frequencies [β€˜102000’, β€˜307200’] and a higher voltage for frequencies [β€˜518400’, β€˜710400’, β€˜921600’, β€˜1132800’, β€˜1326000’, β€˜1479000’] . To confirm my belief, I was trying to find the voltage corresponding to each frequency. Will you be able to check on this frequency to voltage mapping of Jetson Nano 2GB and confirm that this is actually the case?

Best Regards,
Panda

Hello JerryChang,

Could you please let me know, which regulator file will have the CPU core voltage?
I grepped on vdd-cpu in
/sys/kernel/debug/regulator/regulator_summary, but it does not change. It remains the same at 708mV for all the CPU frequencies.

Could you please help me with the regulator file name that holds the current CPU core voltage?

Best Regards,
Saroj Panda

hello sarojpanda.blr,

there’s VDD_CPU for checking CPU power rail.
please refer to Software-Based Power Consumption Modeling for checking details through INA3221 power monitor.

Hello JerryChang,

Thank you for your response. I had checked the documentation.
I am using the Jetson Nano 2GB board.
It seems β€œJetson Nano 2GB does not have an INA3221 power monitor.”

Best Regards,
Saroj Panda