Thread by @lauriewired

The wrong CPU scheduler can kill you.

At one time, I used to work in aerospace. Most aircraft systems are separated into various levels of "criticality".

Safety-critical systems are designed to lose <1 life per 10^9 hours of operation.

The software engineering of said systems is extremely difficult, often requiring use of real-time software.

Hard real-time systems are non-negotiable in timing; they cannot miss target. Think like a car airbag. Soft real-time has a bit more slack.

A real-time os like VxWorks is often used in these applications for their deterministic performance, which also makes it easier to certify.

However, with some creative engineering, the linux kernel, with PREEMPT_RT scheduling, is slowly starting to wiggle into this space.

I'm excited to see more progress for open-source RTOS(s).

Traditionally this has been reserved for proprietary, extremely expensive operating systems; but with modern linux kernels it's possible to experiment with some of these concepts at a hobbyist level.

I've barely even scratched the surface of this space, if you're interested in it, I highly recommend checking out Elana Copperman & Shuah Khan's talk on RT Linux in Safety-Critical Systems, as well as lwn's archive on preemption as a start:
youtube.com/watch?v=ShcEar…
lwn.net/Kernel/Index/#…