Two questions regarding thermal zones

Autonomous Machines Jetson & Embedded Systems Jetson TX2
1

Hi,

I have two questions regarding thermal zones (/sys/devices/virtual/thermal/thermal_zone?):

  • The thermal zone GPU-therm has 7 trip points. The cooling device of the first five zones is tegra-eqos (the next one is a critical so no cooling device and the last one is passive so gpu-balancing). Questions: What is ‘tegra-eqos’ for a cooling device? What does it do?

  • I understand the Thermal-fan-est zone (thermal_zone7) so that this zone is to control the fan in respect to the temperature. Questions is what sensor is used to measure this temperature (where does the content of /sys/devices/virtual/thermal/thermal_zone7/temp comes from)?

Thanks!

2

Hi, as you know, tegra-eqos is one of cooling device which can be connected to thermal zones to implement preset thermal control logic, the control logic is fixed and customer only need to know that it should not be changed.

Originally, thermal-fan-est is used to control PWM of fan by calculating an average value of thermal zones to estimate a value of system temperature, you can refer to thermal design guide to get the default setting of fan control.

3

Hi,

thanks for your reply!

That temp sensor for thermal_zone7 is an average one makes sense. Jetson_TX2_Thermal_Design_Guide_v1.0.pdf says it’s the GPU temperature. But doesn’t matter.

Regarding tegra-eqos: I am asking because when you look at the thermal zones for BCPU (Cortex A57) and MCPU (Denver2) you see that there is no throttling before temperature reaches 93.5°C respective 95.5°C. But the trip points for zone GPU-therm operates already at lower temperatures. Our fear is now that tegra-eqos uses throttling. As a result we would get lower GPU speed already at lower temperatures. So question is: has the tegra-eqos cooling device influence on the GPU performance?

Thanks!

4

No, basically tegra-eqos will not influence GPU performanece.