[foobarian]

With a (conservative) 10k RPM limit, you get a 6ms per rotation. But I would imagine the control must run many times per rotation, so it has a chance to do something different depending on the angle, like a physical camshaft would do. Say you have to re-calculate everything at every 1 degree of rotation, that would give you a 60kHz calculation rate or about 16 microseconds per iteration. I guess that's much more than even the best case in OP's example; I wonder what the compromises are then. Surely they don't punt on the granularity and (say) only do something every 10 degrees? Or worse?

[ncmncm]

About every microcontroller has hardware timer devices that can be set to trigger a signal change with N-nanosecond resolution (N from say 5-50), and even interrupt the core when it is done. The only sharply timing-sensitive bit would be ignition firing, so maybe control those with a hardware timer.

Thing is, you can use the whole repeating schedule, parameterized with adjustments to instantaneous RPM, for many cycles before there is need to check for e.g. throttle input changes.

In between, it is a dance -- shoot some fuel into 1, wait a bit, stop shooting fuel, wait a bit, start closing a valve, wait a bit, schedule a spark, wait a bit, ...

All the settings are chosen, whenever input changes, by table lookup. So tuning means fooling with table entries.