Real-time Linux has arrived in the kernel
Summary
The article describes PREEMPT_RT's inclusion in mainline after decades of development towards more predictable Linux latencies. PREEMPT_RT was largely integrated into the mainline kernel with Linux 6.12. The work spanned more than two decades.
Ideas
- PREEMPT_RT makes further areas of the kernel preemptible.
- Threaded interrupts give the scheduler control over many interrupt paths.
- Priority inheritance limits the blocking of higher-priority tasks.
- Deterministic maximum times count for more than high average throughput.
- Mainline integration reduces external patch sets that have to be maintained permanently.
Insights
- Real time means guaranteed response limits, not merely high speed.
- Inclusion in mainline moves special technology into the ordinary maintenance process.
- Determinism requires a well-matched chain of kernel, drivers and application.
Facts
- Audio, industrial and control systems benefit particularly from bounded latency spikes.
Recommendations
- Measure worst-case latencies under realistic CPU, memory and I/O load.
- Check drivers and firmware separately for non-preemptible delays.
References
Links to the original source and the Web Archive open in a new tab.