How frequently thermal sensors in Odroid XU4 are updated?

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srijeetaM
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How frequently thermal sensors in Odroid XU4 are updated?

Unread post by srijeetaM » Sun Jun 09, 2019 9:03 pm

I am trying to measure the real-time temperature of the CPUs. How frequently are the values get updated in /sys/class/thermal/thermal_zone*/temp file?

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Re: How frequently thermal sensors in Odroid XU4 are updated?

Unread post by odroid » Mon Jun 10, 2019 1:39 pm

There are five sensors for four big A15 cores and one GPU.
The interval of the temperature sensing seems to be defined in this DTS file.
https://github.com/hardkernel/linux/blo ... oints.dtsi
The polling time of each sensor might be 1 seconds and it may take 5 seconds to update the sensor values in worst case.

What is your target sampling rate per each sensors?

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Re: How frequently thermal sensors in Odroid XU4 are updated?

Unread post by srijeetaM » Mon Jun 10, 2019 2:12 pm

Thank you for the reply. My sampling rate is 0.3 sec.

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Re: How frequently thermal sensors in Odroid XU4 are updated?

Unread post by odroid » Mon Jun 10, 2019 3:32 pm

I see. We will check the sysfs device driver to know how frequently updates the values.

Edit: According to the TMU driver source code, you can sample the temperature via sysfs up to 10 times per seconds at least.
So 300msec of interval should not be a problem.

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