How frequently thermal sensors in Odroid XU4 are updated?

Post Reply
srijeetaM
Posts: 8
Joined: Thu Jun 14, 2018 8:02 pm
languages_spoken: english
ODROIDs: XU-4
Has thanked: 1 time
Been thanked: 0
Contact:

How frequently thermal sensors in Odroid XU4 are updated?

Post by srijeetaM »

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?

User avatar
odroid
Site Admin
Posts: 37403
Joined: Fri Feb 22, 2013 11:14 pm
languages_spoken: English, Korean
ODROIDs: ODROID
Has thanked: 1797 times
Been thanked: 1143 times
Contact:

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

Post by odroid »

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?

srijeetaM
Posts: 8
Joined: Thu Jun 14, 2018 8:02 pm
languages_spoken: english
ODROIDs: XU-4
Has thanked: 1 time
Been thanked: 0
Contact:

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

Post by srijeetaM »

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

User avatar
odroid
Site Admin
Posts: 37403
Joined: Fri Feb 22, 2013 11:14 pm
languages_spoken: English, Korean
ODROIDs: ODROID
Has thanked: 1797 times
Been thanked: 1143 times
Contact:

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

Post by odroid »

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.

TuxoHolic
Posts: 3
Joined: Mon Dec 07, 2020 12:46 am
languages_spoken: english
ODROIDs: HC4
Has thanked: 0
Been thanked: 0
Contact:

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

Post by TuxoHolic »

Is there libsensors support in mainline for those thermal values? I noticed Debian Buster kernel 4.19 does not find anything with sensors-detect. I'll test it in Bullseye 5.10 if that mainline commit happened later.

htop relies on libsensor support to display cpu temp values, it did not sound like they where interested in grabbing the centi degree values from thermal_zone[0-4]/temp.

Post Reply

Return to “Hardware and peripherals”

Who is online

Users browsing this forum: No registered users and 2 guests