Granularity of Microprocessor Thermal Management: A Technical ReportReport
Process technology scaling, poor supply voltage scaling and the resultant exponential increase in power density have made temperature a first-class design constraint in today�s microprocessors. An interesting question in the context of thermal management and multi-core architectures is about the correct size granularity of thermal management. It is known that the silicon substrate acts as a spatial low-pass filter for temperature. This means that if blocks with very high power density are small enough (for e.g., if they are below a �cut-off� size), they do not cause hot spots. This paper investigates this phenomenon analytically and presents a discussion through three microarchitectural examples. First is a thermal study of a many-core architecture which illustrates the thermal benefit of many small cores as opposed to a few large cores. This study also explores the effect of local vs. global thermal management. Second is an investigation of whether high aspect ratio sub-blocks such as cache lines can become hot spots due to pathological code behaviour. Third is an exploration of thermal sensor accuracy as a function of the number of sensors and a characterization of two sensor interpolation schemes as a means to reduce sensor errors.
All rights reserved (no additional license for public reuse)
Sankaranarayanan, Karthik, Wei Huang, Mircea Stan, Hossein HajHariri, Robert Ribando, and Kevin Skadron. "Granularity of Microprocessor Thermal Management: A Technical Report." University of Virginia Dept. of Computer Science Tech Report (2009).
University of Virginia, Department of Computer Science