EE382C Embedded Software Systems
Process Networks

Lecture

• Lecture on Process Networks available as slides 9 to 28 of the lecture Dataflow Languages in PowerPoint and PDF formats

• Scheduling Kahn Process Networks

• Park's Bounded Memory Scheduling

Supplemental Information

• Edward A. Lee, The Problem with Threads, Technical Report, University of California, Berkeley, January 10, 2006

• An Introduction to a Mathematical Model of Dataflow
• The Process Network Domain in Ptolemy

Scheduling

• Slides 10-13 of Undecidability and Dataflow Scheduling by Prof. Edward A. Lee from UC Berkeley
• Notes Undecidability, Part 2 from UC Berkeley
• Notes on Scheduling Synchronous and Boolean Dataflow Graphs

1. Dataflow and finite state machine models. A hierarchical combination of these might be a good solution. We have an experimental formalism called heterochronous dataflow that is expressive with regard to control, but decidable like SDF (and hence, in principle, amenable to synthesis). See paper by Girault, Lee, and Lee on the Ptolemy website.
2. Synchronous/Reactive. Dataflow-ish in flavor, but better at control.
3. Synchronous/Reactive (SR) and Process Networks (PN) models, with PN at the top level. SR provides fairly tightly coupled concurrency, which may not match your architecture well. We have done very little experimentation with SR + PN, but it seems promising. Some people advocate this sort of "globally asynchronous, locally synchronous (GALS)" approach.
4. Timed Multitasking. Aimed at implementation using priority-driven RTOSs, but with a more deterministic model of computation than that offered by threads and semaphores, the standard RTOS-based development strategy.