Reconfigurable Real-Time Middleware for Distributed Cyber-Physical Systems with Aperiodic Events

Different distributed cyber-physical systems must handle aperiodic and periodic events with diverse requirements. While existing real-time middleware such as Real-Time CORBA has shown promise as a platform for distributed systems with time constraints, it lacks flexible configuration mechanisms needed to manage end-to-end timing easily for a wide range of different cyber-physical systems with both aperiodic and periodic events. The primary contribution of this work is the design, implementation and performance evaluation of the first configurable component middleware services for admission control and load balancing of aperiodic and periodic event handling in distributed cyber-physical systems. Empirical results demonstrate the need for, and the effectiveness of, our configurable component middleware approach in supporting different applications with aperiodic and periodic events, and providing a flexible software platform for distributed cyber-physical systems with end-to-end timing constraints

9. Real-Time: Basic Concepts

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Configurable Component Middleware for Distributed Real-Time Systems with Aperiodic and Periodic Tasks

Many distributed real-time applications must handle mixed periodic and aperiodic tasks with diverse requirements. However, existing middleware lacks flexible configuration mechanisms needed to manage end-to-end timing easily for a wide range of different applications with both periodic and aperiodic tasks. The primary contribution of this work is the design, implementation and performance evaluation of the first configurable component middleware services for admission control and load balancing of aperiodic and periodic tasks in distributed real-time systems. Empirical results demonstrate the need for and effectiveness of our configurable component middleware approach in supporting different applications with periodic and aperiodic tasks

Linux in Industrial Control Systems

Today the Linux operating system has become a real alternative for industrial control systems. Linux supports all layers in control systems starting with Real-Time or embedded systems for data acquisition, following with treatment, storage, communication and data adaptation, and finally, with supervision and user interfaces. In the last years the Linux development has grown being incorporated in several industrial systems demonstrating high performance, availability and stability for complex processes in chemical, automobile or petrol industries. In many of these industries Linux architectures have been tested and validated successfully. The new CERN policy supporting Linux, as well as the emergence of cheap and robust Linux solutions, motivates its implementation in our safety control and supervision systems in the near future

Merging Real-Time and Control Theory for Improving the Performance of Embedded Control Systems

This report describes the work carried out within the research project ``Merging Real-Time and Control Theory for Improving the Performance of Embedded Control Systems''. The overall objective of the work has been to develop integrated control and scheduling methods for improving the performance of real-time control systems with limited resources. The work has fallen into three categories. First, overrun methods for control tasks has been investigated. Specifically, a reservation-based scheduling concept called the Control Server has been further developed, and control experiments on a ball-and-place process have been performed. Second, the issue of jitter in real-time control systems has been explored. The concept of Jitter Margin has been introduced as a link between control stability theory and scheduling theory. In this context, best-case response-time analysis under earliest-deadline-first scheduling has been researched. Third, some development work on the S.Ha.R.K. real-time kernel has been performed. The rate-monotonic and earliest-deadline-first scheduling modules have been extended, and new modules for the elastic task model and the control server model have been implemented

Design and development of deadline based scheduling mechanisms for multiprocessor systems

Multiprocessor systems are nowadays de facto standard for both personal computers and server workstations. Benefits of multicore technology will be used in the next few years for embedded devices and cellular phones as well. Linux, as a General Purpose Operating System (GPOS), must support many different hardware platform, from workstations to mobile devices. Unfortu- nately, Linux has not been designed to be a Real-Time Operating System (RTOS). As a consequence, time-sensitive (e.g. audio/video players) or sim- ply real-time interactive applications, may suffer degradations in their QoS. In this thesis we extend the implementation of the “Earliest Deadline First” algorithm in the Linux kernel from single processor to multicore systems, allowing processes migration among the CPUs. We also discuss the design choices and present the experimental results that show the potential of our work

Real-time system overheads : a literature overview

In most contemporary systems there are several jobs concurrently competing for shared resources, such as a processor, memory, network, sensors or other devices. Sharing a resource between several jobs requires synchronizing the jobs, specifying when which job will have access to the resource. A common synchronization method is scheduling. Executing a schedule requires switching resource assignments between the jobs, which is usually referred to as context switching. The overheads associated with scheduling and context switching are part of the system overheads. Initially, in the spirit of keeping things simple, real-time systems analysis abstracted from many details, including the overheads incurred by the operating system. This has led to inherently opti-mistic results, i.e. accepting collections of jobs, which if executed on a real system will fail to meet all the constraints. In this paper we consider a less idealized platform by taking some practical aspects into account. We present an overview of literature dealing with real-time system overheads, in particular the scheduling and context switch overheads. We focus on sharing a single timely resource, such as a processor, in the context of Fixed Priority Preemptive Scheduling. We treat in detail the overhead

1. Introduction

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Vulnerability Analysis and Mitigation of Directed Timing Inference Based Attacks on Time-Triggered Systems

Much effort has been put into improving the predictability of real-time systems, especially in safety-critical environments, which provides designers with a rich set of methods and tools to attest safety in situations with no or a limited number of accidental faults. However, with increasing connectivity of real-time systems and a wide availability of increasingly sophisticated exploits, security and, in particular, the consequences of predictability on security become concerns of equal importance. Time-triggered scheduling with offline constructed tables provides determinism and simplifies timing inference, however, at the same time, time-triggered scheduling creates vulnerabilities by allowing attackers to target their attacks to specific, deterministically scheduled and possibly safety-critical tasks. In this paper, we analyze the severity of these vulnerabilities by assuming successful compromise of a subset of the tasks running in a real-time system and by investigating the attack potential that attackers gain from them. Moreover, we discuss two ways to mitigate direct attacks: slot-level online randomization of schedules, and offline schedule-diversification. We evaluate these mitigation strategies with a real-world case study to show their practicability for mitigating not only accidentally malicious behavior, but also malicious behavior triggered by attackers on purpose