Process-variation aware mapping of real-time streaming applications to MPSoCs for improved yield

Abstract

As technology scales, the impact of process variation on the maximum supported frequency (FMAX) of individual cores in a MPSoC becomes more pronounced. Task allocation without variation-aware performance analysis can result in a significant loss in yield, defined as the number of manufactured chips satisfying the application timing requirement. We propose variation-aware task allocation for real-time streaming applications modeled as task graphs. Our solutions are primarily based on the throughput requirement, which is the most important timing requirement in many real-time streaming applications. The three main contributions of this paper are: 1) Using data flow graphs that are well-suited for modeling and analysis of real-time streaming applications, we explicitly model task execution both in terms of clock cycles (which is independent of variation) and seconds (which does depend on the variation of the resource), which we connect by an explicit binding. 2) We present two approaches for optimizing the yield. The approaches give different results at different costs. 3) We present exhaustive and heuristic algorithms that implement the optimization approaches. Our variation-aware mapping algorithms are tested on models of real applications, and are compared to the mapping methods that are unaware of hardware variation. Our results demonstrate yield improvements of up to 50% with an average of 31%, showing the effectiveness of our approaches.