A Multi-Level Approach to Reduce the Impact of NBTI on Processor Functional Units

摘要

NBTI is one of the most important silicon reliability problems facing processor designers today. The impact of NBTI can be mitigated at both the circuit and microarchitecture levels. In this paper, we propose a multi-level optimization approach, combining techniques at the circuit and microarchitecture levels, for reducing the impact of NBTI on the functional units (FUs) of a high-performance processor core. We perform SPICE simulations to evaluate the impact of circuit-level design optimizations to reduce the NBTI guardband in terms of area, delay, and power. We then propose a set of NBTI-aware dynamic instruction scheduling policies at the microarchitecture level and quantify their impact on application performance and guardband reduction through execution-driven simulation. We show that carefully combining techniques at both these levels provides the most attractive solution to reducing the guardband while imposing the least overhead in terms of area, power, delay, and application performance.