Shared memory implementations of synchronous dataflow specifications

Abstract

There has been a proliferation of block-diagram environments for specifying and prototyping DSP systems. These include tools from academia like Ptolemy and GRAPE, and commercial tools like SPW from Cadence Design Systems, Cossap from Synopsys, and the HP ADS tool from HP. The block diagram languages used in these environments are usually based on dataflow semantics because various subsets of dataflow have proven to be good matches for expressing and modeling signal processing systems. In particular synchronous dataflow (SDF) has been found to be a particularly good match for expressing multirate signal processing systems. One of the key problems that arises during synthesis from an SDF specification is scheduling. Past work on scheduling from SDF has focused on optimization of program memory and buffer memory. However, no attempt was made for overlaying or sharing buffers. In this paper we formally tackle the problem of generating optimally compact schedules for SDF graphs, that also attempt to minimize buffering memory under the assumption that buffers will be shared. This will result in schedules whose data memory usage is drastically lower (up to 83%) than methods in the past have achieved.