Gang FTP scheduling of periodic and parallel rigid real-time tasks

TL;DR

This paper develops exact schedulability tests for specific FTP Gang scheduling subclasses of periodic parallel rigid tasks and analyzes their predictability, extending definitions for recurrent tasks.

Contribution

It provides the first exact schedulability tests for FTP Gang schedulers and explores their predictability properties, extending task definitions.

Findings

Exact schedulability tests for FTP Gang subclasses

Gang FJP schedulers are not predictable

Certain subclasses are predictable

Abstract

In this paper we consider the scheduling of periodic and parallel rigid tasks. We provide (and prove correct) an exact schedulability test for Fixed Task Priority (FTP) Gang scheduler sub-classes: Parallelism Monotonic, Idling, Limited Gang, and Limited Slack Reclaiming. Additionally, we study the predictability of our schedulers: we show that Gang FJP schedulers are not predictable and we identify several sub-classes which are actually predictable. Moreover, we extend the definition of rigid, moldable and malleable jobs to recurrent tasks.