Scheduling hardware/software systems using symbolic techniques

Abstract

In this paper, a scheduling method for heterogeneous embedded systems is developed. At first, an internal representation model called FunSrate is presented which enables the explicit representation of nondeterminism and scheduling using a combination of functions and state machines. The new scheduling method is able to deal with mixed data/control Row specifications and takes into account different mechanisms of non-determinism as occurring in the design of embedded systems. Constraints imposed by other already implemented components are respected. Tbe scheduling approach avoids the explicit ennmeration of execution paths by using symbolic techniques and gnarantees to find a deadlock-free and bounded schedule if one exists. The generated schedule consists of statically scheduled basic blocks which are dynamically called at run time.

Symbolic quasi-static scheduling of actor-oriented SystemC models

“…In recent years, techniques related to quasi-static scheduling using dataflow specifications [2], restricted Petri nets [4], [7], [14], [15], or FunState [19] were presented. Key difference between these approaches and our proposal for scheduling is the underlying abstract model.…”

“…E.g., whenever an output transition in free-choice Petri nets [14] or equal conflict nets [15] is enabled, all output transitions of the originating place are enabled. A similar approach is taken by Strehl et al [19] by defining conflict states in FunState models.…”

“…The symbolic QSS approach presented in [19] seems to be the most promising one for actor-oriented SystemC designs and we used it as a basis for our proposed scheduling procedure. But there are two major drawbacks with conflict states as used in the FunState approach: (1) each transition leaving a conflict state results in a path search while scheduling (and therewith in at least one transition in the scheduler automaton), and (2) all transitions must have exactly the same demands on input tokens.…”

Scheduling with bus access optimization for distributed embedded systems

“…The representation is used as a basis for derivation and validation of internal timing constraints for real-time embedded systems. In [39] and [40], an internal design representation is presented that is able to capture mixed data/control flow specifications. It combines dataflow properties with finite-state machine behavior.…”

“…It combines dataflow properties with finite-state machine behavior. The scheduling algorithm discussed in [39] handles a subset of the proposed representation. Timing aspects are ignored and only software scheduling on a single processor system is considered.…”