A method for avoiding loops while decomposing the task description graph in system-level synthesis

Abstract

In system-level synthesis, the graph describing the task may consist of a great number of vertices, thus the design algorithms (e.g. hardware-software partitioning, pipeline synthesis, etc.) may become extremely complicated. This difficulty is relaxed by decomposing the task description graph that is usually unavoidable in system-level synthesis. The decomposing algorithms unite certain vertices of the graph, thus the resulting graph consists of less vertices. However, loops may appear in the decomposed graph, even if the original graph was loop-free, that endangers the efficiency of the design algorithms. We propose an algorithm that generates allowable cuts. We prove that any decomposition made along these cuts always yields a loopfree graph. The method is demonstrated on a simple example. Incorporating optimization criteria in the cut generation is also discussed.

A Modified Inertial Method for Loop-free Decomposition of Acyclic Directed Graphs

“…We propose a strategy different than the one in [12], that also guarantees loop-free result, which we prove in Section 2. We assign a coordinate to each node, i.e.…”

“…A loop-free decomposition algorithm has already been proposed in [12]. This algorithm creates a cutting list based on a heuristic algorithm, and the decomposition is based on this cutting list.…”

“…We propose an algorithm that helps to find the cuts in polynomial time and also attempts to minimize a given cost function. In this case the cost function is considered during the decomposition, and not in a preprocessing step as in [12]. We demonstrate the algorithm on a graph consisting of 20 nodes with a cost function that attempts to find balanced segments, and another one that attempts to find balanced segments with minimal number of edges along the cuts.…”