In this paper we consider the scheduling problem of hard real-time systems composed of periodic constrained-deadline tasks upon identical multiprocessor platforms. We assume that tasks are scheduled by using the global-EDF scheduler. We establish an exact schedulability test for this scheduler by exploiting on the one hand its predictability property and by providing on the other hand a feasibility interval so that if it is possible to find a valid schedule for all the jobs contained in this interval, then the whole system will be stamped feasible. In addition, we show by means of a counterexample that the feasibility interval, and thus the schedulability test, proposed by Leung [Leung 1989] is incorrect and we show which arguments are actually incorrect.
In real-time systems, schedulability tests are utilized to provide timing guarantees. However, for self-suspending task sets, current suspension-aware schedulability tests are limited to Task-Level Fixed-Priority~(TFP) scheduling or Earliest-Deadline-First~(EDF) with constrained-deadline task systems. In this work we provide a unifying schedulability test for the uniprocessor version of Global EDF-Like (GEL) schedulers and arbitrary-deadline task sets. A large body of existing scheduling algorithms can be considered as EDF-Like, such as EDF, First-In-First-Out~(FIFO), Earliest-Quasi-Deadline-F…
Due to the increasing complexity seen in both workloads and hardware resources in state-of-the-art embedded systems, developing efficient real-time schedulers and the corresponding schedulability tests becomes rather challenging. Although close to optimal schedulability performance can be achieved for supporting simple system models in practice, adding any small complexity element into the problem context such as non-preemption or resource heterogeneity would cause significant pessimism, which may not be eliminated by any existing scheduling technique. In this paper, we present LINTS^RT, a lea…
Feasibility Tests for Recurrent Real-Time Tasks in the Sporadic DAG Model
在[Baruah et al.,在Proceedings of IEEE实时的【形】Systems Symposium 2012中],用于表示要在多处理器平台上执行的循环优先约束任务,其中每个循环任务由有向无环图(DAG)、周期和相对截止期限来建模。DAG的每个顶点表示一个顺序作业,而DAG的边表示这些作业之间的优先约束。DAG的所有作业都是同时发布的,并且必须在某个指定的相对截止日期内完成。任务可以以这种方式释放作业无限次,连续的释放至少间隔指定的时间段。可行性问题是确定这样的经常性任务是否可以被调度为总是满足指定数量的专用处理器上的所有截止日期。在[Baruah et al.,2012年]。本文的主要贡献是考虑多任务的情况下。我们表明,EDF有一个加速比界为2-1/m,其中m是处理器的数量。此外,我们提出了多项式和伪多项式的可扩展性测试,不同的有效性,以确定是否可以由EDF调度一组零星的DAG任务,以满足指定数量的处理器上的所有最后期限。
Systems-on-Chips (SoCs) that power autonomous vehicles (AVs) must meet stringent performance and safety requirements prior to deployment. With increasing complexity in AV applications, the system needs to meet these real-time demands of multiple safety-critical applications simultaneously. A typical AV-SoC is a heterogeneous multiprocessor consisting of accelerators supported by general-purpose cores. Such heterogeneity, while needed for power-performance efficiency, complicates the art of task scheduling. In this paper, we demonstrate that hardware heterogeneity impacts the scheduler's effect…