How useful is a lock-free (not wait-free) approach in a real-time context? The point is that any thread contending on lock-free data is liable to starve, so the worst-case behavior is still quite bad, no? The only benefit I see is freedom from priority inversion, and that's a fixable problem anyway. Are there other properties of the system that you somehow use to get real-time guarantees?

On the other hand, if you combine interrupt-disabling with a fair lock, then your lock wait time can be bounded in every thread. This is probably only an option inside the kernel, though.

In userspace, and with more threads than CPUs, the lock-free approach probably will save you a lot of context-switching time. It'll probably also be at least as fine-grained as the most fine-grained locking scheme you can come up with, probably with less overhead.

So I'd say that the lock-free approach is an optimistic strategy, and I don't see the benefit except for performance. I say this as someone who really likes lockfree programming.