Jetson TX2 has 2 cpu online but sitting at 0%

Hello,

Our team is currently developing some application on the jetson tx2 and, at the moment, we cannot accurately benchmark it because 2 of the board’s CPU are sitting a 0% (although online), here is a screenshots to show the problem, this frequency is measured on jtop as well as the ubuntu system monitor.

Note that, from what we can tell, they are not offline:

  1. On jtop, offline CPUs are shown with a red OFF sign (which is clearly not the case here)
  2. We have (repeatedly) executed the following command

echo 1 > /sys/devices/system/cpu/cpu[12]/online

This 0% percent frequency stays even during intensive tasks (i.e. running TensorFlow graphs).

Does anyone have any idea what is going on and how to fix it?

If you run the command “cat /proc/cmdline”, you will find the arguments passed to the kernel at start. One of those arguments will be “isolcpus=1-2”. If you remove that argument, then you won’t find the issue. Sometimes an argument appears twice, and so if you remove the argument and there is a second one (probably from device tree), then removal of just the one isolcpus won’t change the behavior. If you place the last isolcpus without an argument, then you will fix the problem regardless of how many times it is in the command line. In your “/boot/extlinux/extlinux.conf” I recommend you edit wherever you see “isolcpus=1-2” (the “APPEND” key/value pair) to instead be:
isolcpus=
(no "1-2…this clears the isolcpus)

2 Likes

I work with @tomgautot and I confirm the solution. Thank you @linuxdev !