Global Scheduling of Multi-Mode Real-Time Applications upon Multiprocessor Platforms

TL;DR

This paper introduces two protocols for managing mode transitions in multi-mode real-time systems on multiprocessors, with formal schedulability analyses ensuring timing requirements are met during transitions.

Contribution

It proposes novel run-time protocols for mode transitions in multi-mode real-time systems on multiprocessors, with formal schedulability guarantees for different scheduler types.

Findings

Protocols ensure schedulability during mode transitions

Formal analyses validate timing guarantees

Applicable to uniform and identical multiprocessor platforms

Abstract

Multi-mode real-time systems are those which support applications with different modes of operation, where each mode is characterized by a specific set of tasks. At run-time, such systems can, at any time, be requested to switch from its current operating mode to another mode (called "new mode") by replacing the current set of tasks with that of the new-mode. Thereby, ensuring that all the timing requirements are met not only requires that a schedulability test is performed on the tasks of each mode but also that (i) a protocol for transitioning from one mode to another is specified and (ii) a schedulability test for each transition is performed. We propose two distinct protocols that manage the mode transitions upon uniform and identical multiprocessor platforms at run-time, each specific to distinct task requirements. For each protocol, we formally establish schedulability analyses that indicate beforehand whether all the timing requirements will be met during any mode transition of the system. This is performed assuming both Fixed-Task-Priority and Fixed-Job-Priority schedulers.