Really depends on your requirements. One important distinction is that hard-realtime doesn't necessarily mean low-latency or low-jitter. It just means that fail

Really depends on your requirements. One important distinction is that hard-realtime doesn't necessarily mean low-latency or low-jitter. It just means that failing to meet a deadline is a failure of the whole system. You are right that absent other demands on the processor, polling can usually offer the lowest-latency, lowest-jitter response from a system.