Scheduling and analysis of real-time task graph models with nested locks

• Locking protocol is a crucial component in scheduling of real-time systems. The digraph real-time task model (DRT) is the state-of-the-art graph-based task model, which is a generalization of most previous real-time task models. To our best knowledge, the only work addressing resource sharing problem in DRT task model proposes a resource sharing protocol, called ACP, as well as a scheduling strategy EDF+ACP. Although EDF+ACP is optimal for scheduling DRT tasks with non-nested resource access, it cannot handle the situation of nested resource accesses. In this paper, we propose a new protocol, called N-ACP, by modifying ACP to manage nested resource accesses in task graph models. We apply N-ACP to EDF scheduling to obtain a new scheduling strategy EDF+N-ACP. We develop schedulability analysis techniques for EDF+N-ACP and evaluate its performance by a widely-used quantitative metrics speedup factor. We derive its speedup factor as a function of the maximal nesting level of resource accesses in the system.

Ämnesord

NATURVETENSKAP  -- Data- och informationsvetenskap -- Datavetenskap (hsv//swe)

NATURAL SCIENCES  -- Computer and Information Sciences -- Computer Sciences (hsv//eng)

Nyckelord

Locking protocol

Nested resource sharing

Real-time system

Schedulability analysis

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