Partial Reconfiguration for Design Optimization

TL;DR

This paper explores how partial reconfiguration (PR) in FPGAs can optimize resource utilization and improve performance-area trade-offs by dynamically reallocating resources, supported by an analytical model and case studies.

Contribution

It introduces an analytical model to determine when and how PR can enhance FPGA design performance compared to ASIC-style fixed designs.

Findings

PR can reduce resource under-utilization

The model accurately predicts PR benefits

Case studies validate the model's effectiveness

Abstract

FPGA designers have traditionally shared a similar design methodology with ASIC designers. Most notably, at design time, FPGA designers commit to a fixed allocation of logic resources to modules in a design. At runtime, some of the occupied resources could be left idle or under-utilized due to hard-to-avoid sources of inefficiencies (e.g., operation dependencies). With partial reconfiguration (PR), FPGA resources can be re-allocated over time. Therefore, using PR, a designer can attempt to reduce idleness and under-utilization with better area-time scheduling. In this paper, we explain when, how, and why PR-style designs can improve over the performance-area Pareto front of ASIC-style designs (without PR). We first introduce the concept of area-time volume to explain why PR-style designs can improve upon ASIC-style designs. We identify resource under-utilization as an opportunity that can be exploited by PR-style designs. We then present a first-order analytical model to help a designer decide if a PR-style design can be beneficial. When it is the case, the model points to the most suitable PR execution strategy and provides an estimate of the improvement. The model is validated in three case studies.