Maximizing Yield per Area of Highly Parallel CMPs Using Hardware Redundancy

The manufacturing yield of chip multiprocessors (CMPs) has become a significant problem as more transistors are integrated onto a single die and the defect rate keeps increasing for “end-of-Moore” nano-scale CMOS technologies. Since such CMP designs usually have significant structural symmetry, adding spare copies to these should be an effective method for increasing yield per area, as is the case for memories. However, a systematic approach to add spare copies to optimize CMP yield per area has never been developed, primarily due to the lack of: 1) a general model of CMP architectures and 2) a practically-useable model for computing areas of chip versions with different configurations of spare copies. This paper develops such models and, in conjunction with a systematic approach for enumerating a wide range of spare configurations, uses these to compute the area overhead and yield for each configuration. In particular, this paper proposes a general spare cores sharing technique to maximize yield per area of any CMP by efficiently traversing the design space for adding spare cores. Experimental results show that the advantage of the proposed approach over traditional approaches increases with continued technology scaling. Specifically, the proposed approach achieves (2times ) yields per area over previous approaches for 32 nm and 22 nm technologies. Also, the obtained yield per area values provided by our approach are around 70% of that obtained for the ideal scenario where defect density is zero and no redundancy is added.