Fault-tolerant Real-time Applications Research Articles

Stability and Performance Analysis of Clock Synchronization in FlexRay

This paper presents a case study on the performance of a distributed clock synchronization algorithm used in FlexRay, a communication protocol designed to meet the requirements of dependable, fault-tolerant real-time applications. The FlexRay industry consortium drives forward the standardization of a fault-tolerant communication system for advanced automotive applications. In this case study we will analyze two different configurations for typical automotive applications by means of simulation. The focus of the simulation experiments is the assessment of performance and stability of the FlexRay clock synchronization algorithm in the presence of varying clock drift rates. For the analysis we will use SIDERA, a simulation model for time-triggered distributed systems

Solving the group priority inversion problem in a timed asynchronous system

Considers the priority inversion problem in an actively replicated system. Priority inversion was originally defined in the context of nonreplicated systems. Therefore, we first introduce the concept of group priority inversion, which extends the concept of (local) priority inversion to the context of a group of processors that perform an actively replicated processing. We then present the properties of a request scheduling protocol to enforce a total ordering for the processing of requests while avoiding group priority inversions. These properties have been implemented in a protocol that relies on a timed asynchronous system model equipped with a failure detector of the class /spl diams/S. The proposed solution allows us to replicate a critical server while ensuring that the processing of all the incoming requests is consistent (mechanisms for solving the atomic broadcast problem) and predictable (mechanisms for solving the group priority inversion problem). Thus, the described request scheduling protocol is a key component which can be used to develop fault-tolerant real-time applications in a timed asynchronous system.

Using Ravenscar to support fault-tolerant real-time applications

Recently, a framework was proposed intended to support the development of replicated and distributed Ravenscar applications. This framework provides a transparent abstraction for application replication, allowing applications to be developed without considering replication and distribution issues. However, it is also necessary to assess if the Ravenscar profile is expressive enough for the implementation of this complex middleware. Therefore, this paper presents some conclusions that were drawn on the implementation of a prototype of the framework.

Software management in a MODULA-2 environment for a multiprocessor, embedded system

Realtime, multiprocessor embedded systems are one application area where response times, throughput, reliability and fault-tolerance constitute the major design criteria. Hence the distribution and management of the application software is a critical function. A prototype loosely-coupled multiprocessor system has been designed and implemented for use in fault-tolerant realtime applications. This paper discusses the organization and structure of the total system, concentrating in particular on the software requirements of the communication and executive (kernel) functions. The communication system is based on a token passing bus protocol for use with single-board computers connected via a fast parallel bus. The kernel is designed to support functional partitioning of application programs, and can be implemented using standard compilers. No special multiprocessing features are required. Most of the software for this system has been written in modula-2, though assembly language programming has been used in a few specialized areas.

Logic programs and an experimental architecture for their execution: Oldfield, J VIEE Proc. E Vol 133 No 3 (May 1986) pp 163–167

Realtime, multiprocessor embedded systems are one application area where response times, throughput, reliability and fault-tolerance constitute the major design criteria. Hence the distribution and management of the application software is a critical function. A prototype loosely-coupled multiprocessor system has been designed and implemented for use in fault-tolerant realtime applications. This paper discusses the organization and structure of the total system, concentrating in particular on the software requirements of the communication and executive (kernel) functions. The communication system is based on a token passing bus protocol for use with single-board computers connected via a fast parallel bus. The kernel is designed to support functional partitioning of application programs, and can be implemented using standard compilers. No special multiprocessing features are required. Most of the software for this system has been written in modula-2, though assembly language programming has been used in a few specialized areas.