Instructions to test real-time capabilities

Requirements

To configure a Linux real-time system please follow these instructions.

TODO: add support for other RTOS

These are the options that allows to configure the process real-time settings:

priority: changes the process priority and set a real-time FIFO priority. This will set the priority of the thread where the ROS 2 executor is running.
cpu-affinity: binds the application to a specific CPU core by setting a CPU mask. For example, to bind the process or thread to CPU 3 (or 2 starting from 0) we set the CPU mask to 4 (100 in binary).
lock-memory: pre-faults memory until no more page faults are seen. This usually allocated a high amount of memory so make sure there is enough memory in the system.
lock-memory-size: specifies the amount of memory we want to pre-allocate. For example lock-memory-size 100 pre-allocates 100 MB.
config-child-threads: specifies if the RMW middleware child threads will inherit the main process settings. This applies for priority and cpu-affinity options.. For example, if config-child-threads False is set, only the main thread where the ROS executor is set with the priority and cpu-affinity options. If, config-child-threads True is set, the DDS threads will also inherit the same priority and CPU affinity configuration than the main thread.

Example using ros2 launch:

ros2 launch pendulum_bringup pendulum_bringup.launch.py priority:=80 cpu-affinity:=4 lock-memory-size:=100 config-child-threads:=True

Example using the executable command line arguments:

ros2 run pendulum_demo pendulum_demo --priority 80 --cpu-affinity:=4 --lock-memory-size 100 --config-child-threads True

TODO