Reservation-Based Federated Scheduling for Parallel Real-Time Tasks

TL;DR

This paper introduces a reservation-based federated scheduling algorithm for parallel real-time DAG tasks with arbitrary deadlines, offering a generalized approach with proven efficiency bounds and broad applicability.

Contribution

It generalizes federated scheduling for parallel DAG tasks, providing a reservation-based approach with constant speedup guarantees and compatibility with existing schedulers.

Findings

Reservation-based federated scheduling dominates traditional federated scheduling.

The proposed algorithm has a constant speedup factor relative to optimal DAG schedulers.

It can be integrated with schedulers designed for non-parallel sporadic tasks.

Abstract

This paper considers the scheduling of parallel real-time tasks with arbitrary-deadlines. Each job of a parallel task is described as a directed acyclic graph (DAG). In contrast to prior work in this area, where decomposition-based scheduling algorithms are proposed based on the DAG-structure and inter-task interference is analyzed as self-suspending behavior, this paper generalizes the federated scheduling approach. We propose a reservation-based algorithm, called reservation-based federated scheduling, that dominates federated scheduling. We provide general constraints for the design of such systems and prove that reservation-based federated scheduling has a constant speedup factor with respect to any optimal DAG task scheduler. Furthermore, the presented algorithm can be used in conjunction with any scheduler and scheduling analysis suitable for ordinary arbitrary-deadline sporadic task sets, i.e., without parallelism.