Reserving CPU Cores on Nvidia Jetson Orin Nano Dev Board

Issue Overview

Users are experiencing difficulties in reserving CPU cores on the Nvidia Jetson Orin Nano for specific processes, particularly for real-time processing tasks. The main symptoms include:

• Inability to isolate cores: Users want to run the operating system on a single core while reserving others for dedicated tasks.
• Interrupt management: Difficulty in defining which core should handle specific interrupts (e.g., GPIO interrupts).
• Programming challenges: Users are unsure how to start threads on isolated cores using C++ or other programming languages.

The issue typically arises during the setup phase or while attempting to run specific applications that require real-time processing capabilities. Users have varying levels of success, with some reporting partial solutions using commands like taskset and sched_setaffinity(). The impact of this problem significantly affects the performance of time-sensitive applications, leading to potential delays and inefficiencies in processing.

Possible Causes

Several factors could contribute to the difficulties users face when trying to reserve CPU cores:

• Configuration Errors: Incorrect settings in the extlinux.conf file can prevent proper core isolation.
• Driver Issues: Incompatibilities or bugs in the Linux kernel or drivers may hinder core management.
• Software Bugs: The operating system or specific applications may not support multi-core management efficiently.
• User Misconfigurations: Users may not be familiar with Linux commands or configurations necessary for isolating CPU cores.
• Environmental Factors: Power supply issues or overheating can affect system stability and performance.

Each of these causes can lead to the observed problems by preventing the operating system from effectively managing CPU resources.

Troubleshooting Steps, Solutions & Fixes

To address the issue of reserving CPU cores, users can follow these comprehensive troubleshooting steps:

1. Modify extlinux.conf for Core Isolation:

   • Open the extlinux.conf file located in /boot/.
   • Add the following line to isolate specific CPUs:

     isolcpus=1,2  # Replace with desired core numbers
     

2. Use taskset Command:

   • To assign a process to a specific core, use:

     taskset -c <core_number> <command>
     

   • For example, to run a Python script on core 2:

     taskset -c 2 python3 my_script.py
     

3. Using sched_setaffinity() in C++:

   • To start a thread on an isolated core, use the following code snippet:

     #include <sched.h>
     
     cpu_set_t cpuset;
     CPU_ZERO(&cpuset);
     CPU_SET(<core_number>, &cpuset); // Replace with desired core number
     
     pthread_t thread;
     pthread_create(&thread, NULL, my_function, NULL);
     pthread_setaffinity_np(thread, sizeof(cpu_set_t), &cpuset);
     

4. Check for Kernel Support:

   • Ensure that your kernel supports CPU isolation features. You can check this by running:

     grep CONFIG_SCHED_SMT /boot/config-$(uname -r)
     

5. Review Documentation and Community Resources:

   • Refer to Nvidia’s official documentation and forums for updates regarding JetPack versions and known issues.
   • Engage with community discussions for shared experiences and solutions.

6. Best Practices for Future Prevention:

   • Regularly update your Jetson’s software and firmware.
   • Document configuration changes to easily revert if issues arise.
   • Test configurations incrementally to identify what works best for your specific application needs.

Following these steps should help users effectively isolate CPU cores on their Nvidia Jetson Orin Nano Dev Board and improve their experience with real-time processing tasks. If issues persist, further investigation into hardware compatibility or software updates may be necessary.