constant ~10% CPU usage with irq/76-249000 on both Xavier A&B


we found just today there is constant ~10% CPU usage with irq/76-249000 with both Xavier A&B. a lot of interrupts were generated for irq 76 as shown in /proc/interrupts. please advise how to fix.


Dear jerryc_sf,

Could you please let me know below? Thanks.

  1. What release are they using?
  2. What’s the use scenario?
    Is this idle on a desk, some application running, in a car?

Hi Steve,

I am using the firmware installed with sdkmanager 0.9.9-2351. linux kernel uname -r: 4.9.111-rt76-tegra

the system was installed in vehicle. It developed this behavior a few weeks ago and has not disappeared since then. we removed all accessories but behavior remains unchanged.

Attached please see the pictures of the behavior. please let us know what may have caused it and how to fix?


Dear jerryc_sf,

Could you please let me know the system pdk version with below command on the system?

$cat /etc/nvidia/version-ubuntu-rootfs.txt

nvidia@tegra-ubuntu:~$ cat /etc/nvidia/version-ubuntu-rootfs.txt

Dear jerryc_sf,

Thank you for the info.

Could you please provide the ifconfig output? Thanks.

attached. thanks

Dear jerryc_sf,

Could you please let me know both Xavier A&B are flashed with the same? Thanks.

they were flashed the same. aurix firmware also upgraded as well. it developed this problem a few weeks ago. previously no problem.

Dear jerryc_sf,

According to the capture files, this is from the DriveAGX without any lidar/radar? 14.2G is huge receiving data.
Could you please help to re-check after reboot or flash DriveAGX if possible? Thanks.

Confirmed the cause from LiDAR. However, cpu usage was immediately changed to ~12% as soon as LiDAR was connected to Ethernet switch (no applications was run to receive the lidar data).

Hi jerryc_sf,

Some lidar uses broadcast packets so regardless of whether application is running or not the packets will be taken by the CPU and pass on to the network protocol. Hence CPU load from IRQ from lidar traffic is expected, by internal experiment, 10% IRQ CPU load looks normal.