Dr. Karam S. Chatha

From the Arizona State University, AZ

Authors

Dr. Karam S. Chatha - Arizona State University, AZ

Abstract

Increased device densities and device counts fuelled by semiconductor technology scaling have led to a sharp increase in power consumption and heat flux in current day microprocessors. The heat flux (or power density) in state-of-art microprocessors is currently in the range of 100-150 W/cm2 and is expected to rise to upward of 250 W/cm2 by 2010. Even processors aimed at hand held embedded devices such as PDAs, smart phones will have power densities close to 100 W/cm2.

The high heat flux has contributed toward a rise in die temperatures. Die temperatures on current day microprocessors can easily reach 120o C. Increased die temperatures adversely affect device reliability, performance and can potentially lead to thermal runaway. Existing design approaches have primarily addressed thermal challenges by incorporating micro-architectural features that dynamically detect thermal emergencies, and respond by limiting the core or unit activity.

The talk will address system-level thermal aware design in the context of embedded system applications. Embedded system applications are differentiated from general purpose computing by their well defined functionalities. Consequently, they enable the incorporation of system-level thermal-aware scheduling techniques at design time. Such techniques vary the power consumption profile of the task set to limit the peak temperature of the application. The techniques utilize a thermal model of the processor and exploit the dynamic voltage frequency scaling and dynamic power management features of current day embedded processors. The talk will introduce the system-level thermal aware scheduling problem and discuss its complexity. The talk will then present automated design techniques to solve the problem. Experimental results with representative applications will be presented to demonstrate the effectiveness of the techniques. The talk will conclude with a discussion of open design problems.