Utilities for real-time tests and applications

[carlossvg]

I created this issue to discuss utilities that may be used in real-time tests tools .

Acceptance Criteria

• Decide what to do with https://github.com/ros2/realtime_support
• Decide if it makes sense to add commonly used support tools in a specific package
  • Process configuration
  • Statistics: Use libstatistics_collector instead of custom utilities https://gitlab.com/ApexAI/performance_test/-/blob/master/performance_test/src/utilities/statistics_tracker.hpp, https://github.com/hsgwa/ros2_timer_latency_measurement/blob/master/src/util.cpp

[carlossvg]

I would like to start the discussion by reviewing the current status of the real-time_support repository.

• rttest
  • Description
    • rttest is an existing library developed to instrument the update loop of a real-time process and report on various metrics described here. However, it contains code specific to Linux pthreads in its current state. If it is to be used in this work, the library needs to be generalized to support other operating systems.
    • rttest is a minimal tool for instrumenting and running tests for synchronous real-time systems. It provides utilities for measuring and plotting jitter, latency, and missed deadlines. It also provides a library with macros for instrumenting code. It is designed with real-time Linux-based systems in mind, such as Preempt RT kernel.
    • Usage example https://github.com/ros2/realtime_support/blob/master/rttest/examples/example_loop.c
  • Comments
    • It would be good to separate RT settings (scheduling and memory locking) and, spin instrumentation and result analysis
    • It would be good to generalize the tools to support multiple operating sytems (i.e: Linux, QNX).
    • Currently, other applications use their own way to configure these settings
      • https://gitlab.com/ApexAI/performance_test/-/blob/master/performance_test/src/utilities/rt_enabler.hpp
      • https://github.com/ros2/demos/blob/master/pendulum_control/src/pendulum_demo.cpp#L273
      • https://github.com/hsgwa/ros2_timer_latency_measurement/blob/master/src/init_thread.cpp#L43
      • https://github.com/bmwcarit/ros_realtime_tests/blob/master/rt_tests_support/include/rt_tests_support/PrioritySwitcher.h
• tlsf_cpp
  • Description:
    • The realtime_support package will offer real-time memory allocators and example code for real-time ROS 2. An example of the ROS 2 allocator API using the Two Level Segregate Fit allocator is currently available in realtime_support.
  • Comments
    • Is there is any plan to continue with this work?

[carlossvg]

@razr @LanderU TODO:

• Discuss with the community how useful are these utilities
  • Memory locking
  • Thread scheduling configuration
  • ROS executable instrumentation
  • real-time memory allocators
• Do we want to update this or create new packages?

[nightduck]

Action Items

• Get admin control of repository
• Spin out subpackages
• Refactor it to be a readme with documentation, and a repos referencing realtime packages hosted elsewhere