Validating Delay Bounds in Networks on Chip: Tightness and Pitfalls

Analytical methods for estimating on-chip network performance can be very useful to accelerate and simplify the design process of Networks on Chip. However, in order to increase the confidence in these approaches it is fundamental to perform systematic studies that assess their potential. We present a methodical investigation on the tightness between analytical end-to-end delay bounds and worst-case simulation latencies in various scenarios. We first introduce our network calculus based analytical technique to derive per-flow communication delay bounds. Then, we examine the worst-case performance analysis process in NoCs outlining the major aspects that affect the tightness. Finally, experimental results confirm our deductions and allow us to provide general guidelines to avoid pitfalls in the validation process of analytical delay bounds.