Workload capacity considering NBTI degradation in multi-core systems

As device feature sizes continue to shrink, long-term reliability such as Negative Bias Temperature Instability (NBTI) leads to low yields and short mean-time-to-failure (MTTF) in multi-core systems. This paper proposes a new workload balancing scheme based on device level fractional NBTI model to balance the workload among active cores while relaxing stressed ones. The proposed method employs the Capacity Rate (CR) provided by the NBTI model, applies Dynamic Zoning (DZ) algorithm to group cores into zones to process task flows, and then uses Dynamic Task Scheduling (DTS) to allocate tasks in each zone with balanced workload and minimum communication cost. Experimental results on 64-core system show that by allowing a small part of the cores to relax over a short time period (10 seconds), the proposed methodology improves multi-core system yield (percentage of core failures) by 20%, while extending MTTF by 30% with insignificant degradation in performance (less than 3%).