Solving Out-of-Order Communication in Kahn Process Networks

Abstract

The Compaan compiler framework automates the transformation of DSP applications written in Matlab into Kahn Process Networks (KPNs). These KPNs express the signal processing applications in a parallel distributed way making them more suitable for mapping onto parallel architectures. A simple instance of a generated KPN by Compaan is a Producer process that communicates with a Consumer process via a FIFO buffer, with the Consumer reading data from the FIFO using a blocking read. When the sequence of producing data is different from the sequence of consuming data, a simple FIFO is not sufficient to implement the communication. For such case, extra storage and control are needed at the consumer side. This paper presents a compile approach that determines whether a FIFO buffer is sufficient for every Producer/Consumer pair of a Compaan-generated KPN. When additional memory is required, we provide an address generation mechanism to perform the reordering and furthermore give a lower bound on the amount of memory needed to perform the reordering. The presented approach is based on the Ehrhart theory