An Exact and Sustainable Analysis of Non-preemptive Scheduling

This paper provides an exact and sustainable schedulability test for a set of non-preemptive jobs scheduled with a fixed-job-priority (FJP) policy upon a uniprocessor. Both classic work-conserving and recent non-work-conserving schedulers are supported. Jobs may exhibit both release jitter and execution time variation. Both best- and worst-case response time bounds are derived. No prior response-time analysis (RTA) for this general setting is both exact and sustainable, nor does any prior RTA support non-work-conserving schedulers. The proposed analysis works by building a schedule graph that precisely abstracts all possible execution scenarios. Key to deferring the state-space explosion problem is a novel path-merging technique that collapses similar scenarios without giving up analysis precision. In an empirical evaluation with randomly generated workloads based on an automotive benchmark, the method is shown to scale to 30+ periodic tasks with thousands of jobs (per hyperperiod).