Gerardo Lamastra

Task synchronization in reservation-based real-time systems

In this paper, we present the BandWidth Inheritance (BWI) protocol, a new strategy for scheduling real-time tasks in dynamic systems, which extends the resource reservation framework to systems where tasks can interact through shared resources. The proposed protocol provides temporal isolation between independent groups of tasks and enables a schedulability analysis for guaranteeing the performance of hard real-time tasks. We show that BWI is the natural extension of the well-known priority inheritance protocol to dynamic reservation systems. A formal analysis of the protocol is presented and a guarantee test for hard real-time tasks is proposed that takes into account the case in which hard real-time tasks interact with soft real-time tasks.

A bandwidth inheritance algorithm for real-time task synchronization in open systems

In this paper, we present algorithm BandWidth Inheritance (BWI), a new scheduling strategy that extends the bandwidth reservation approach to systems where tasks can interact through shared resources. The proposed algorithm provides temporal isolation between independent groups of tasks, and enables a schedulability analysis for guaranteeing the performance of realtime tasks. After showing that BWI is the natural extension of the well-known Priority Inheritance Protocol to dynamic reservation systems, a formal analysis of the algorithm is presented, and simple guarantee tests for hard real-time tasks are proposed.

An object-oriented tool for simulating distributed real-time control systems

This paper presents an object‐oriented software tool, called RTSIM, aimed at simulating real‐time embedded controllers. The tool consists of a collection of C++ libraries permitting a separate specification of the functional behaviour of the controller and of the hardware/software architecture to be used for its deployment. In particular, it is possible to provide an accurate modelling of the concurrent architecture of the control tasks and of the run‐time support offered by the operating system for the real‐time scheduling of the shared resources (CPU, memory buffers and network links). In this way, it is possible to compare different scheduling solutions by evaluating their simulated performance directly in the domain of the control application. Moreover, the tool can be utilized to tune up design parameters such as the activation frequencies of the tasks. The application of the tool is shown in a meaningful case study. Copyright

HARTIK 3.0: a portable system for developing real-time applications

This paper describes the features of the HARTIK system, a hard real-time kernel designed to help the development of real-time applications, ranging from classical hard control systems to soft multimedia, distributed systems. The portability, the predictability and the flexibility in expressing timing constraints allow the application designer to explore a broad set of solutions both from a hardware and software perspective. A toolkit has also been developed to support the design phase. The kernel supports 16-bit and 32-bit Intel 80/spl times/86 processors, DEC Alpha AXP-PCI-33, and can be easily ported to other different hardware architectures, such as microcontrollers and embedded systems. The relevant features offered by the kernel include direct specification of timing constraints, such us period and deadlines, coexistence of tasks with different criticalness, dynamic scheduling of periodic and aperiodic tasks, bounded blocking time on shared resources, prevention of deadlock and chained blocking; asynchronous, time bounded communication paradigm for exchanging data among tasks having different execution rates.

Simulation and tracing of hybrid task sets on distributed systems

This paper describes a tool for the design, simulation and analysis of real-time systems, ranging from simple scenarios with a few types of tasks on a single node to very complex architectures consisting of multiple nodes interconnected with a network and sharing a set of hardware and software resources. The tool is based on a discrete event simulation library, a scripting language describing the system load and the relevant measures, and a graphical interface providing user-friendly interaction with the simulator.

Robot control in hard real-time environment

This paper describes a software architecture aimed at the development of complex robotic applications with stringent real-time constraints. The proposed methodology is based on a modular design approach, in which high-level processes are developed from elementary sensory-motor activities, carried our at lower layers of a hierarchical control system. The control software is organized in a number of layers, which add new capabilities to the robot system and allow the user to program an application at different levels of abstraction. At the lowest layer, the execution of all computational activities is supported by a hard real-time kernel, which provides predictable scheduling of periodic and aperiodic tasks. The flexibility of the proposed approach is shown through real robotic applications.

A Scheduling Simulator for Real-Time Distributed System

Abstract This paper describes a tool for the design, simulation and analysis of realtime systems, ranging from simple scenarios with a few types of tasks on a single node to very complex architectures consisting of multiple nodes interconnected with a network and sharing a set of hardware and software resources. The tool includes a discrete event simulation library, a scripting language for describing the system load and the relevant measures, and a graphical interface providing user-friendly interaction with the simulator.