OldSpot: A Pre-RTL Model for Fine-Grained Aging and Lifetime Optimization

Modern technologies have been experiencing evergrowing power densities as they scale down, raising temperatures and increasing aging and reliability concerns. High-level simulation is necessary in order to measure aging effects on lifetime. Existing simulation tools are inadequate due to their assumptions about homogeneity and failure tolerance. These limitations reduce their accuracy in modeling heterogeneous systems or systems with shared resources, leading to lifetime overestimation. We propose a new open-source tool called "OldSpot" that relaxes these assumptions and integrates low-level models for aging mechanisms with high-level reliability modeling techniques to enable fine-grained lifetime simulation, and then show how it can be used to improve the lifetime of a multicore system by duplicating functional units rather than adding extra cores. Using this structural duplication, we show area improvement by up to 13% while eliminating performance degradation due to failing resources. Additionally, we use OldSpot to show that lifetime and temperature are not perfectly correlated and that aging must be simulated along with temperature for optimal lifetime.