Reducing the cost of redundant execution in safety-critical systems using relaxed dedication

We introduce on-demand redundancy, a set of architectural techniques that leverage the tightly-coupled nature of components in systems-on-chip to reduce the cost of safety-critical systems. On-demand redundancy eases the assumptions that traditionally segregate the execution of critical and non-critical tasks (NCTs), making resources available for critical tasks at potentially arbitrary points in both space and time, and otherwise freeing resources to execute non-critical tasks when critical tasks are not executing. Relaxed dedication is one such technique that allows non-critical tasks to execute on critical task resources. Our results demonstrate that for a wide variety of applications and architectures, relaxed dedication is more cost-effective than a traditional approach that employs dedicated resources executing in lockstep. Applied to dual-modular redundancy (DMR), relaxed dedication exposes 73% more NCT cycles than traditional DMR on average, across a wide variety of usage scenarios.