EtherCAT Real-Time Optimization

Real-Time Optimization and Debugging

7.1 PREEMPT_RT

For applications with strict real-time requirements, such as motion control, a PREEMPT_RT kernel is recommended. For real-time kernel configuration in this repository, see the RTLinux Real-Time System Development Guide.

A real-time kernel can reduce scheduling latency, but it cannot replace proper thread design, network drivers, CPU isolation, and device configuration.

7.2 CPU and Scheduling Optimization

Common optimization measures include:

1. Bind the cyclic thread to a dedicated CPU.
2. Isolate that CPU from normal tasks and load balancing.
3. Bind the relevant network interface IRQs to planned CPUs.
4. Use SCHED_FIFO and select a reasonable thread priority.
5. Set the CPU frequency governor to performance.
6. Evaluate whether deep CPU Idle states need to be disabled.
7. Avoid running graphical interfaces, log compression, and high-load services on a real-time CPU.

Display threads and IRQs:

ps -eLo pid,tid,cls,rtprio,psr,comm
cat /proc/interrupts
taskset -pc <pid>

When setting CPU affinity, select CPUs according to the SoC topology, IRQ distribution, and application load. Do not copy CPU numbers directly from another platform.

7.3 Performance Mode

Set the CPU frequency governor:

for governor in /sys/devices/system/cpu/cpufreq/policy*/scaling_governor; do
  echo performance | sudo tee "$governor"
done

For product deployment, make the setting persistent through a system service and evaluate power consumption and thermal performance.