does HN have any thoughts on Xenomai[1]? I've been using it for years without issue. On a BeagleBone Black, it typically gives jitter on the order of hundreds

does HN have any thoughts on Xenomai[1]? I've been using it for years without issue. On a BeagleBone Black, it typically gives jitter on the order of hundreds of nanoseconds. I would consider it "hard" real-time (as do they). I'm able to schedule tasks periodically on the scale of tens of microseconds, and they never get missed. It differs from this in that Real-Time Linux attempts to make Linux itself preemptive, whereas Xenomai is essentially its own kernel, running Linux as a task on top. It provides an ABI which allows you to run your own tasks alongside or at higher prio than Linux. This sidesteps the `printk()` issue, for instance, since Xenomai doesn't care. It will gladly context switch out of printk in order to run your tasks. The downside is that you can't make normal syscalls while inside of the Xenomai context. Well... you can, but obviously this invalidates the realtime model. For example, calling `printf()` or `malloc()` inside of a xenomai task is not preemptable. The Xenomai ABI does its best to replicate everything you may need as far as syscalls, which works great as long as you're happy doing your own heap allocations. [1]: https://xenomai.org/ https://xenomai.org/