Official Real-Time Kernel Integration after 20 Years of Contributions

After 20 Years of Working on Linux Real-Time Kernel, SUSE Welcomes the Official Inclusion of Real-Time Capabilities to the Linux Kernel. The integration of real-time (RT) capabilities is set to transform industries that depend on deterministic performance. The inclusion of RT into the mainline Linux kernel marks a historic achievement, one that has been in the making for over two decades. Real-time Linux has finally become officially part of the kernel, and this breakthrough will make real-time capabilities more accessible and streamline their adoption in enterprises. SUSE has been a key player in this long journey, contributing expertise, development, and resources along the way.

The Importance of Real-Time Linux

Real-time computing refers to systems that require precise timing to operate correctly. In fields like telecommunications, automotive systems, industrial automation, and even financial trading, the ability for a system to respond in a predictable way to inputs in microseconds is mission-critical. Linux’s flexibility and open-source nature made it an ideal candidate for RT workloads, but its kernel was not originally designed for deterministic behavior. This is where SUSE’s involvement in RT kernel development has been crucial.

20 Years of RT Development: SUSE’s Contribution to the PREEMPT_RT Patchset

The RT patchset for the Linux kernel has been in development for more than 20 years—a two-decade-long effort to make the Linux kernel capable of deterministic, real-time performance.Over these two decades, companies like SUSE consistently contributed to the development of real-time Linux, providing customized real-time kernel versions to enterprise customers while advancing the PREEMPT_RT patchset. In the final stages, SUSE made a vital contribution that helped unlock the final merge of the PREEMPT_RT patchset.
Just a few years ago, only one critical piece of the puzzle remained: a sophisticated rewrite of the infrastructure related to printk()—the console output. It was one of the hardest challenges to overcome. This task fell to Petr Mladek, a SUSE Kernel Engineer, in collaboration with John Ogness and Thomas Gleixner from Linutronix, who together led the effort to solve this final hurdle. This collaboration highlights the exceptional cooperation within the Linux kernel community.

A Hard Nut to Crack: SUSE’s Contribution

SUSE’s engineers invested time, energy, and creativity in solving the complex last piece of the puzzle: printk() which needed a complete, very sophisticated rewrite. This feature is essential for real-time operations as it handles console output in the Linux kernel. Those contributions also guided the entire community working on this implementation, ensuring that everything was aligned and on the right track.
A few days ago, this final missing piece was merged into the Linux kernel, as seen in the official merge.
Once this merge occurred, it unblocked the final integration of the PREEMPT_RT patchset into the Linux kernel, completing a journey that started 20 years ago. The final merge of PREEMPT_RT is documented here.

SUSE’s Broader Contributions to Real Time Linux

While the printk() rewrite was a significant milestone, SUSE’s contributions to real-time Linux extend far beyond this achievement. Over the years, SUSE has consistently supported the development of the PREEMPT_RT patchset and actively worked on enhancing critical kernel features required for real-time workloads. In addition to upstream contributions, SUSE has long provided, and continues to provide, SUSE Linux Enterprise Real Time to ensure that customers can support mission-critical workloads with the reliability and performance demanded by industries requiring deterministic performance.

Real-Time Ready SUSE Linux Enabling New Scenarios.

SUSE’s commitment to real-time Linux is also reflected in its products, including the real-time kernel in their most recent container host, SUSE Linux Micro, to support new real-time containerized scenarios and empower new solutions requiring real-time, such as SUSE Edge products. This enterprise offering provides organizations with a hardened, real-time capable Linux distribution that ensures the deterministic behavior required for mission-critical applications. With the PREEMPT_RT patchset now fully integrated into the mainline kernel, customers can expect even better performance and reliability.

Looking Ahead

As real-time capabilities become part of the Linux kernel’s official feature set, the future of real-time computing on Linux looks promising. This integration makes real-time easier to implement and maintain, streamlining innovation within the Linux kernel community. SUSE remains committed to refining real-time performance and ensuring that industries requiring deterministic response times can depend on Linux for their critical workloads.

Conclusion

The inclusion of real-time Linux in the mainline kernel is a triumph for the open-source community. SUSE has played a key role in making this happen.  SUSE’s solution to one of the final hurdles, the printk() rewrite, was the crowning achievement of their broader contributions. SUSE’s contributions to RT Linux demonstrate the company’s commitment to advancing open-source technology for enterprise use. After 20 years of development, real-time Linux is now officially part of the kernel, and SUSE is proud to have been part of this journey.

To explore what’s new in SUSE’s real-time ready container host, read the SUSE Linux Micro 6 announcement.