Design of Heterogeneous Multiprocessor Systems for Real-Time Applications

Project no: A2-9805

Petru Eles, Zebo Peng

Linköping University, Department of Computer and Information Science, Embedded Systems Laboratory (ESLAB)

Application as pdf, ps , support letter from Ericsson Radio Systems AB.

Support: 1 PhD student for 2 years decided 98-08-20.

Start 99-09-01 with Sorin Manolache as graduate student.

Report 99-08-02 as pdf, ps

First year report 00-11-30.

Local web: http://www.ida.liu.se/~eslab/rts2.html

 

Industry contacts

Jonas Plantin

Ericsson Radio Systems

X/R

Stockholm

Project: Design of Heterogeneous Multiprocessor Systems for Real-Time Applications

 

Erik Stoy Erik.Stoy@era.ericsson.se

Ericsson Radio Systems

X/R

Stockholm

Project: Design of Heterogeneous Multiprocessor Systems for Real-Time Applications

Overview

The final goal of this research is to develop a design environment which supports the specification, verification, analysis, and synthesis of heterogeneous hardware/software systems for real-time applications. One of the important features of such a design environment is that it starts from specifications at a high level of abstraction and supports the designer from the early phases of the design. The input specification only describes the overall functionality of the designed system and includes the imposed constraints (timing, power consumption, cost, etc.). Starting from such a system specification, the design environment supports the automatic or interactive exploration of a large design space which leads to high performance and cost effective solutions. At the same time, early detection of design errors and the use of synthesis tools which take into consideration timing constraints, drastically reduces the number of functional and timing errors detected in later design phases and, thus, avoids expensive revisions of the design. The following issues have been identified in the project proposal as being of particular interest: system modelling and specification, performance estimation and scheduling, design space exploration. The project has been defined and conducted in close cooperation with Ericsson Radio Systems in Kista (department for Radio and Systems Technology). At the suggestion of our industrial partners we have adopted a GSM Base-Station Transceiver, as a case study.

Results and contributions

1. System specification.
In order to manage large specifications in an efficient manner and to support system level reuse, an object-oriented methodology based on UML has been investigated with special emphasis on simulation in the context of real-time constraints and on reusability aspects. The model of a GSM Base-Station Transceiver has been elaborated. This work has been of great interest for the industrial partners. It also led to interesting conclusions concerning the suitability of UML and the underlying methodology, for specification of embedded applications. Last but not least it was an opportunity for the PhD student involved in the project to study a large and complex application in the telecom area.

2. Performance estimation & scheduling
One important input we got from our industrial partners is that performance estimation and scheduling (as part of the system design process) based on deterministic worst case execution times is not a realistic approach for their application area. Therefore, we propose a probabilistic approach to system design which has to be applied gradually to the main phases of the design process: allocation, mapping, scheduling. Currently, our research is focused on analytical performance estimation of mono-processor task schedules, where the task execution times are known only probabilistically. We intend to extend this to multi-processor task schedules in the near future. Task scheduling of stochastic tasks raises additional challenges compared to classical worst-case execution time task models. We address the problem under as general assumptions as possible. As an underlying mathematical model for the analysis, we use stochastic processes, in particular, generalized semi-Markov chains. We developed an algorithm to derive the stochastic process out of the initial task specification. The stochastic process - a DAG - is constructed in a memory and time efficient way. This is extremely important, because of the complexity of the problem, and several techniques have been applied in order to achieve a performance which allows the analysis of large systems.

Co-operation

Within project

There have been several meetings both during preparation of the project and after starting it. The industrial partners have actively participated in the definition of a case study based on the GSM base station transceiver. A presentatio of the UML model for the basestation transceiver, implemented as a part of the project, has been organized at Ericsson Radio Systems in Kista.

Joint graduate courses with ECSEL in Linköping

• Advanced issues in computer architectures
• Design of embedded real-time systems

Publications

1. Razvan Jigorea, Sorin Manolache, Petru Eles and Zebo Peng. "Modelling of Real-Time Embedded Systems in an Object-Oriented Design Environment with UML", Proc. IEEE International Symposium on Object-oriented Real-time Distributed Computing (ISORC 2000), Newport Beach, California, 2000.
2. Sorin Manolache: Using UML to Model Heterogenous Real-Time Systems M.Sc. Thesis. Linköping 1999.