Q&A about Preempt RT
summary
Preempt RT is mostly upstream but cannot yet be enabled on mainline because missing printk console pieces and threaded printk enablement remain; the patch set is about 80 patches and includes roughly 4,000 lines in the serial 8250 area. Transparent Huge Pages currently stay disabled until THP code is fixed for RT, softirq priorities remain unchanged by default, networking is moving toward threaded NAPI, and the TTY is unfixable for hard real‑time serial I/O — a non‑TTY path or new driver (i915 replacement) is the practical route.
AI-written summary · about
chapters (23)
- 0:00Introduction
- 0:22Printk limitations in Preempt RT
- 1:26Duct tape engineering in kernel
- 2:49Preempt RT patches upstream status
- 3:57Threaded printk infrastructure progress
- 4:40Transparent huge pages compatibility
- 6:08Prioritizing real-time over THP
- 7:14Software interrupts default priorities
- 8:25NAPI design flaws real-time impact
- 9:28Networking stack threaded NAPI
- 11:12TTY layer real-time unsuitability
- 13:45Alternatives to TTY for serial
- 15:52i915 driver real-time challenges
- 17:18Why i915 driver unfixable
- 18:45Kernel train wrecks duct tape patterns
- 19:49Areas to avoid in real-time
- 21:33File systems real-time constraints
- 22:58Real-time data streaming use cases
- 24:46Network stack tuning for real-time
- 25:52Intel's role in Preempt RT
- 27:1525 years of Preempt RT
- 28:39Cyclictest real-time examples
- 30:47Testing real-time without hardware
