Statistical Framework for Designing On-Chip Thermal Sensing Infrastructure in Nanoscale Systems

Thermal/power issues have become increasingly important with more and more transistors being placed on a single chip. Many dynamic thermal/power management techniques have been proposed to address such issues but they all depend heavily on accurate knowledge of the chip´s thermal state during runtime. In this paper, we describe a unified statistical framework for designing an on-chip thermal sensing infrastructure that can be used to track the chip´s thermal state at runtime. Specifically, we address the following problems in this statistical framework: 1) sensor placement; 2) sensor data compression; 3) sensor data fusion; and 4) overall interplay. Our methods exploit the correlations between temperatures in different parts of the chip to drive sensor placement, data compression, and data fusion in both noiseless and noisy sensor cases. Our framework is also capable of choosing the appropriate degree of compression for each sensor while accounting for their local space constraints during deployment. The experimental results show that the root-mean-square error of the thermal estimates produced by our sensing infrastructure is on average 35% better than an equivalent system that uses a range-based placement scheme and a uniform compression scheme. It took our methods at most about 9 s to decide the overall solution for placement, compression, and data fusion at the design stage. This demonstrates the effectiveness and applicability of our unified statistical design methodology.