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Adding real-time to Linux with Preempt-RT

Mar 22, 2013 — by Rick Lehrbaum 10,409 views has published a short Q&A with Steven Rostedt, kernel developer at Red Hat and maintainer of the stable Linux real-time patch. Rostedt discusses issues such as “hard” vs “soft” real-time, what the Preempt-RT patch can and can’t do, and how to get started using it. editor Libby Clark writes…

    When embedded projects call for for a real-time operating system, Linux developers often turn to PREEMPT-RT, the real-time kernel patch, to get it done.

    “The PREEMPT_RT patch (aka the -rt patch or RT patch) makes Linux into a real-time system,” said Steven Rostedt, a Linux kernel developer at Red Hat and maintainer of the stable version of the real-time Linux kernel patch.

    The thing is, in most cases real-time requirements on embedded projects can be met without turning to a real-time operating system, he said via email. To developers, a real-time system “does what you expect it to do when you expect it to do it.” That’s all.

Clark then asks, and Rostedt answers, these questions about the RT patch…


  • As Dave Stewart said in an ABS panel discussion, people often assume that embedded means real-time but that’s not always the case. He said, “There’s been a dawning realization that you can achieve the vast majority of what you need to with embedded without a classically-oriented real-time system.” Do you agree?
  • When and how does real-time Linux come into embedded development?
  • I heard from Steve Sakoman that embedded Linux doesn’t work when the device has hard real-time requirements (and in some cases, any real-time requirements). How does the real-time patch meet those requirements when embedded Linux falls short?
  • How is the RT patch used in embedded development?
  • What’s your advice to embedded developers who want to use the RT patch?
  • When does it make more sense to work with a distro that has already incorporated the RT patch, versus starting from scratch?
  • What challenges still remain for RT Linux in embedded development and how are they being addressed?

Read LIbby Clark’s complete Q&A with Steve Rostedt here.

Rostedt’s ELC presentation, “Inside the RT Patch,” can be viewed below. The accompanying slides can be downloaded here (PDF file).

Inside the RT Patch


Learn more about real-time Linux

For lots of information about the PREEMPT_RT patch and real-time Linux in general — including FAQs, tips, how-to’s, community news, and more — visit the Real-time Linux Wiki.

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