Synthesis of heterogeneous pipelined multiprocessor systems using ILP: jpeg case study

Streaming applications can be implemented with a pipeline of processors. Each processor in the pipeline can be an application Specific Instruction Set Processor (ASIP) with the result being a heterogeneous pipelined MPSoC system. Since ASIPs can be of differing configurations, finding the optimal set of configurations for a multiprocessor architecture is a difficult problem. In this paper, we obtain an optimal system design for a set of processors which execute a multimedia application. The variables in the system are the presence or absence of different additional instructions and differing cache configurations for each of the processors. The problem is formulated as a 0-1 Integer Linear Programming (ILP) problem. To reduce the complexity of the ILP formulation, inferior ASIP configurations are efficiently pruned so that the solution could be reached quickly. Given a system runtime constraint, the proposed methodology finds a design with minimal area. We integrated this design methodology into a commercial design flow, and performed a case study upon the JPEG encoding application. We obtained 15 optimal designs subject to 15 different runtime constraints, each in less than 100 seconds from more than 4.2 x 1013 design points.