UC Irvine

Over the last few decades, chip performance has increased steadily due to continuous and aggressive technology scaling. However, it leaves chips quite vulnerable to several issues at the same time. High power densities in some particular areas spread across a chip might result in hotspots and thermal gradients, and these can lead to permanent damage to the chip and also can reduce the reliability of the entire system using the chip. As a result, a large number of dynamic thermal management (DTM) solutions have been proposed in recent years for use in multi-core architectures, and accurate temperature information over the entire chip area has become indispensable especially for fine-grain DTM solutions. Naturally, on-chip thermal sensors came to play an important role in providing accurate information on the thermal distribution of a chip, but there still remain some issues regarding the allocation of on-chip thermal sensors. Due to power, die area, and routing issues, it is preferable to limit the total number of on-chip thermal sensors on a die. Their placement also needs to be considered carefully in order to increase the accuracy of full-chip thermal profile reconstruction, especially when just a small number of thermal sensors can be deployed. In addition, it would be preferable to have some way to improve the reading accuracy of low power, small-sized on-chip thermal sensors that usually tend to have very limited accuracy in temperature readings.

In this work, an issue will be firstly addressed regarding how to improve the reading accuracy of a low power, small-sized on-chip thermal sensor such as Ring-Oscillator (RO) based sensors at runtime on a software level. Secondly, a question of how to allocate a proper number of thermal sensors on a die in order to get the accurate full-chip scale temperature information on the run is addressed. Additionally, a temperature-aware routing method for global interconnects to minimize the signal propagation delay and also to reduce the probability of chip failure due to electromigration is presented at the end.