Towards a Unified Framework for Modeling and Analyzing User-Defined Online Non-Preemptive Scheduling Policies

This paper presents a unified formal framework, called ReTA, that allows users to define scheduling problems using a user-friendly domain-specific language (DSL) and automatically obtain response times of jobs in return. ReTA supports user-defined online scheduling policies (beyond work-conserving or priority-based scheduling) for heterogeneous computing resource types with multiple instances per type (e.g., multiple CPU cores, GPUs, DSPs, and FPGAs on one single chip), thus supporting global, partitioned, and clustered scheduling. In the current version of ReTA, we focus on non-preemptive periodic tasks as these are susceptible to scheduling anomalies and hence harder to analyze. ReTA performs response-time analysis by constructing a timed labeled transition system (TLTS) from the domain model as a basis for performing a reachability analysis enriched with efficient state-space reduction techniques. Our empirical evaluations show that ReTA identifies up to 50 times more schedulable task sets than fixed-point iteration-based analyses. With a runtime on the order of a few minutes, ReTA produces highly accurate results two-orders of magnitude faster than an exact Timed Automata-based analysis in UPPAAL (e.g., for systems with 16 cores and 32 tasks).