There is a patchset that enables deterministic behaviour on Linux (https://www.linux.com/news/event/elce/2017/2/inside-real-time-linux https://www.linux.com/new

There is a patchset that enables deterministic behaviour on Linux (https://www.linux.com/news/event/elce/2017/2/inside-real-time-linux https://www.linux.com/news/event/elce/2017/2/inside-real-tim... has a few pointers). Much of it has been mainlined, and it does have trustworthy enough commercial backing that it's worth considering at least. That being said, the more typical approach for this, as employed by e.g. RTLinux ( http://www.rtlinux.org/ http://www.rtlinux.org/ -- I'm not endorsing it, it's just the one I'm more familiar with), is to run a hard RTOS along with Linux, running real-time tasks on the RTOS and everything else on Linux. It's a more complex solution, and it's a little unsettling that we've even had to come up with it, but it works surprisingly well. Writing fancy UIs and multimedia applications on top of things like QNX is difficult (not necessarily in terms of learning/development effort, but also in terms of licensing, cost, hardware support etc.), while writing real-time control applications on a patched Linux kernel requires some trips down the kernel rabbit holes, and is hard to get through some certification processes. Companies optimize for whatever they need :).