Alejandro Alonso

A dual-band priority assignment algorithm for dynamic QoS resource management

Future high-quality consumer electronics will contain a number of applications running in a highly dynamic environment, and their execution will need to be efficiently arbitrated by the underlying platform software. The multimedia applications that currently execute in such similar contexts face frequent run-time variations in their resource demands, originated by the greedy nature of the multimedia processing itself. Changes in resource demands are triggered by numerous reasons (e.g. a switch in the input media compression format). Such situations require real-time adaptation mechanisms to adjust the system operation to the new requirements, and this must be done seamlessly to satisfy the user experience. One solution for efficiently managing application execution is to apply quality of service resource management techniques, based on assigning and enforcing resource contracts to applications. Most resource management solutions provide temporal isolation by enforcing resource assignments and avoiding any resource overruns. However, this has a clear limitation over the cost-effective resource usage. This paper presents a simple priority assignment scheme based on uniform priority bands to allow that greedy multimedia tasks incur in safe overruns that increase resource usage and do not threaten the timely execution of non-overrunning tasks. Experimental results show that the proposed priority assignment scheme in combination with a resource accounting mechanism preserves timely multimedia execution and delivery, achieves a higher cost-effective processor usage, and guarantees the execution isolation of non-overrunning tasks.

Mode Change Protocols for Predictable Contract-Based Resource Management in Embedded Multimedia Systems

Media processing in High-Quality Multimedia Embedded Systems (HQMES) has real-time constraints. Timely processing and rendering of video frames and audio samples is essential to meet user expectations. The nature of incoming media suffers unforeseen variations which have different resource requirements. Therefore, HQMES have to integrate policies for efficiently and smoothly adapting to these changes. Mode change protocols allow applications to switch their state (for instance, to transition from one quality level to another) by controlling the way in which the application tasks change from one state to another. This paper provides a solution for timely mode change protocols based on a contract model between applications and the execution platform. A new mode change algorithm, progressive mode change protocol, is introduced for applications with no tolerance to data loss during their transitions. The execution platform is based on a quality of service resource manager (QoSRM) that arbitrates the greedy execution of multimedia applications, and that is implemented on top of the services of a real-time operating system. A task model and a temporal characterization of multimedia application tasks is also presented as the basic platform for the QoSRM operation. Validation experiments show stable execution of applications with the proposed task characterization and progressive mode change protocol.

MultiPARTES: Multicore Virtualization for Mixed-Criticality Systems

Modern embedded applications typically integrate a multitude of functionalities with potentially different criticality levels into a single system. Without appropriate preconditions, the integration of mixed-criticality subsystems can lead to a significant and potentially unacceptable increase of engineering and certification costs. A promising solution is to incorporate mechanisms that establish multiple partitions with strict temporal and spatial separation between the individual partitions. In this approach, subsystems with different levels of criticality can be placed in different partitions and can be verified and validated in isolation. The MultiPARTES FP7 project aims at supporting mixed-criticality integration for embedded systems based on virtualization techniques for heterogeneous multicore processors. A major outcome of the project is the MultiPARTES XtratuM, an open source hyper visor designed as a generic virtualization layer for heterogeneous multicore. MultiPARTES evaluates the developed technology through selected use cases from the offshore wind power, space, visual surveillance, and automotive domains. The impact of MultiPARTES on the targeted domains will be also discussed. In a number of ongoing research initiatives (e.g., RECOMP, ARAMIS, MultiPARTES, CERTAINTY) mixed-criticality integration is considered in multicore processors. Key challenges are the combination of software virtualization and hardware segregation and the extension of partitioning mechanisms to jointly address significant non-functional requirements (e.g., time, energy and power budgets, adaptivity, reliability, safety, security, volume, weight, etc.) along with development and certification methodology.

Reference architecture for robot teleoperation:: development details and practical use

This work has been partially supported by the Spanish Government Programmes for Research in Electrical Power (project PIE-041049), and for Technological Actuation in Industry (PAUTA projects 753/ 95 y 53/96). TRON is supported inside EUREKA– MAINE program (EU1565).

RMI-HRT: remote method invocation - hard real time

Real time systems have a great impact in areas such as: telecommunications, consumer electronics, medical equipment, etc. Additionally, the Java community has defined RTSJ (Real Time Specification for Java) for the development of these systems with Java technology. RTSJ introduces new memory areas to avoid the effect of the garbage collector, improves the scheduling of threads, and provides mechanisms for the asynchronous transfer of control, and protocols to bind the priority inversion, etc. However, RTSJ does not include facilities to develop distributed applications. This is an important limitation that reduces the usage of RTSJ. As a consequence, RMI-HRT (Remote Method Invocation - Hard Real Time) has been developed in the context of the HIJA (High-Integrity Java Applications) project to provide support for distributed applications which are targeted at safety-critical applications. The objective of this paper is to show the most important aspect of RMI-HRT.

MultiPARTES: Multi-core partitioning and virtualization for easing the certification of mixed-criticality systems

Abstract The consumer market is continuously pushing for smarter, faster, more durable and cheaper products with ever more complex and sophisticated functionality. Other fields such as safety–critical and dependable applications are not unaware of these requirements, and even impose others (e.g. certification). In the current multi-core era, industry and research entities are facing the important challenge of fulfilling all these requirements, which often impose the necessity for integrating components with different levels of dependability in a single hardware platform. In this scenario, new concerns appear with respect to safety certification of the resulting mixed-criticality systems (e.g. temporal and spatial isolation). This article describes the research effort that is being conducted within the FP7 MultiPARTES project, which is one of the initiatives launched by the European Commission to explore new solutions for developing certifiable mixed-criticality systems using heterogeneous multi-cores. The article explains the proposed development toolset for such systems, presents a proof-of-concept implementation and shows its applicability in a real-world application that needs to be certified, namely a wind-power turbine.

Two alternative RMI models for real-time distributed applications

Javas popularity, facilities and platform independence have made it an interesting language for the real time community. The RTSJ (real-time specification for Java) is a Java extension to allow the development of real-time systems. RTSJ does not supply any support for the development of real-time distributed systems. The goal of this work is to define support for this type of systems, based on RMI (remote method invocation). However, the high diversity of real-time systems implies that there is not a single RT-RMI definition that satisfies their requirements. This article presents the basics of two real-time RMI approaches: safety critical RMI, to support hard real-time and high integrity requirements, and quality of service RMI for soft real-time systems, which is based on resource reservation to provide some minimal required quality.

Software Architecture for a Robot Teleoperation System

Abstract The success of certain applications heavily depends on its capability to be modified and adapted to different operations and environments. This paper presents the main issues in the development of a robot teleoperation system whose main goal is to operate a robot that performs maintenance activities in nuclear plants. The capability to adapt its operation to different jobs and operational environments is one of the most important requirements. The approach taken is based on the development of a generic software architecture for this kind of systems. A domain analysis was performed for identifying the most commonly used components in these applications. The resulting architecture was implemented integrating code written in different languages (Ada and C) and commercial tools. The resulting architecture has been successfully tested. The robot controller (which is the most important subsystem) has been reused for implementing specialized mechanical robot tools.

The IPTES environment: Support for incremental, heterogeneous and distributed prototyping

This paper summarizes the support for incremental, heterogeneous and distributed prototyping of real time systems developed as a part of the IPTES environment. After describing the overall architecture of the environment and related approaches, the paper focuses on the internal levels of the environment.IPTES environment supports the incremental development of Real-Time Systems under a spiral life cycle model. The user starts from a SA/RT description enhanced with an executable VDM dialect for minispecifications. Both parts are converted into high level timed Petri nets (HLTPN). The partition of the model at the SA/RT level is reflected at the HLTPN as distributed subnets. A distributed prototype execution implies the joint execution of distributed subnets. Finally, some parts of the prototype could be substituted by actual target code and executed with the rest of the prototype. This is the concept of heterogeneous prototype supported by IPTES tools. A communication protocol to allow the interchange of information while executing has been designed and implemented in the IPTES environment.A detailed description of the Real Time Object Communication Layer (RTOC), its constituent primitives and internal algorithms is presented. This discussion provides the background to understand the behavior of the High Level Timed Petri Net Kernel (HLTPNK) to execute distributed subnets and the Run Time Adaptation Kernel (RTAK) to control the execution of target code as users of the RTOC.Finally, the method used to generate successive versions of the protocol and kernel modules in order to reduce the risks during the implementaton is outlined.

QoS-based resource management for ambient intelligence

Future homes will probably be equipped with in-home networks, combining a backbone of wired networks and a large number of devices connected through wireless links, to provide a responsive and supportive environment, known as Ambient Intelligence. Many of the applications provided to the user lean heavily on media processing and streaming data. Therefore it is expected that consumer terminals will play an important role in providing new experiences to the users. Most of the devices have to be very cost and power effective, while digital media processing is able to consume all the resources a device can offer, and more. Typically, the number of applications and the resource needs of the applications change over time. To adapt to these variations, applications have the ability to trade resource usage for quality of service (QoS). QoS based resource management enables these tradeoffs in resource-constrained systems. In this paper we present our QoS approach, and we explore an integrated approach that addresses terminal and network resources, and takes power issues into account.