Home > On-Demand Archives > Q&A Sessions >

Live Q&A - Challenges and techniques to use Linux in Real-Time Systems

Sergio Prado - Watch Now - Duration: 27:12

Live Q&A - Challenges and techniques to use Linux in Real-Time Systems
Sergio Prado
Live Q&A with Sergio Prado for the talk titled Challenges and techniques to use Linux in Real-Time Systems
M↓ MARKDOWN HELP
italicssurround text with
*asterisks*
boldsurround text with
**two asterisks**
hyperlink
[hyperlink](https://example.com)
or just a bare URL
code
surround text with
`backticks`
strikethroughsurround text with
~~two tilde characters~~
quote
prefix with
>

uapeiron
Score: 2 | 10 months ago | 1 reply

Hello Sergio, thank you for the nice presentation. Excuse me If I'm making a wrong conception here but I'm wondering why the developers of the PREEMPT_RT patch decided to implement RR, FIFO, DEADLINE but no Rate-Monotonic (RM) Algorithm for real time scheduling as far as I understand RM guarantees determinism in RTOS while DEADLINE or Earliest Deadline First does not. Thanks for your answer!

sergio_pradoSpeaker
Score: 0 | 10 months ago | 1 reply

I am glad you enjoyed the talk!

Yeah, RMS is one option for real-time scheduling, but I am not sure if it guarantees determinism.

Most algorithms depend on the developer to provide some input (priority, deadline, period, etc) so the algorithm can take decisions - at least until we decide to start adding AI to schedulers! :-)

Having said that, an RMS analysis can be applied to any real-time operating system (including Linux), independent of whether the kernel has an RMS scheduler or not. RMS just says you should define the priority of tasks based on their period (more frequent tasks get a higher priority), and you can do that upfront (at design time). And on Linux, you could use SCHED_FIFO or SCHED_RR to schedule those tasks.

Let me know if you have any further questions.

uapeiron
Score: 0 | 10 months ago | no reply

Thank you so much for your answer it clarifies my doubt!!!

15:39:08	 From  Raul Pando : Sergio, I really enjoyed your presention. I was wondering how frequently you find yourself enabling RT kernel extensions vs conventional kernel in your professional work.
15:41:22	 From  Ulises V : Hello Sergio, thank you for the nice presentation. Excuse me If I'm making a wrong conception here but I'm wondering why the developers of the PREEMPT_RT patch decided to implement RR, FIFO, DEADLINE but no Rate-Monotonic (RM) Algorithm for real time scheduling as far as I understand RM guarantees determinism in RTOS while DEADLINE or Earliest Deadline First does not. Thanks for your answer!
15:45:33	 From  Antonio : You mentioned in your presentation a wide variety of profiling and benchmarking tools for working with the Linux Kernel. Is there a particular one that you can recommend (not only for RT kernels)? Which ones do you use in your projects?
15:51:47	 From  Michael Kirkhart : "Be aware that some POSIX APIs were not designed with RT behavior in mind."  Could you name some examples?
15:58:26	 From  Michael Kirkhart : RAII = Resource Allocation Is Initialization (sorry - I almost got it right): https://en.cppreference.com/w/cpp/language/raii
15:58:32	 From  Stephane   to   Sergio Prado(Direct Message) : Thanks a lot for speaking again this year!
15:58:39	 From  Jacob Beningo : Reacted to "RAII = Resource Allo..." with 👍
15:58:47	 From  Raul Pando : Thanks a lot everyone
15:58:56	 From  Ulises V : Reacted to "Thanks a lot everyon..." with 👍
15:58:58	 From  Antonio : Se ha reaccionado a "Thanks a lot every..." con ❤️

OUR SPONSORS