Electrical Engineering
      and Computer Sciences

Electrical Engineering and Computer Sciences

COLLEGE OF ENGINEERING

UC Berkeley

   

2008 Research Summary

PTIDES: Programming Temporally Integrated Distributed Embedded Systems

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Yang Zhao, Slobodan Matic, Thomas Huining Feng, Jia Zou, Ben Lickly and Edward A. Lee

The PTIDES project, or Programming Temporally Integrated Distributed Embedded Systems, focuses on developing programming models for real-time distributed systems and studying algorithms that can statically check whether a given model is deployable over a network of distributed systems.

This project exploits timed protocols such as NTP and IEEE 1588, where a relatively consistent global notion of time is present in distributed systems. PTIDES uses discrete-event (DE) models as programming specifications for distributed real-time systems and extends discrete-event models with the capability of mapping certain events to physical time. In [1], we use model time to define execution semantics and add constraints that bind certain model time events to physical time. We limit the relationship of model time to physical time to only those circumstances where this relationship is needed, and an execution model that permits out of order processing of events without sacrificing determinacy and without requiring backtracking is explored.

Another project that could potentially prove valuable to PTIDES concerns precision timed (PRET) machines, which emphasize the ability to provide execution time guarantees along with the overall performance of the architecture. In an effort to exploit this design, PTIDES can be used as a multi-tasking scheduling interface that allows a user to write applications that take full advantage of the timing guarantees of the hardware. The main challenges in the design include communicating through input/output interfaces and scheduling interrupts that occur aperiodically. The root of the problem lies in resource contention, and the current effort revolves around building an architecture and scheduler that would take advantage of the actor-orientated approach and discrete-event semantics in order to resolve resource contention.

[1]
Y. Zhao, E. A. Lee, and J. Liu, Programming Temporally Integrated Distributed Embedded Systems, UC Berkeley EECS Department Technical Report No. UCB/EECS-2006-82, May 28 2006.
[2]
S. Edwards and E. A. Lee, The Case for the Precision Timed (PRET) Machine, UC Berkeley EECS Department Technical Report No. UCB/EECS-2006-149, November 17, 2006.