The Art of Software Thermal Management for Embedded Systems
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This book introduces Software Thermal Management (STM) as a means of reducing power consumption in a computing system in order to manage heat, improve component reliability and increase system safety. Readers will benefit from this pragmatic guide to the field of STM for embedded systems and its catalog of software power management techniques. Since thermal management is a key bottleneck in embedded systems design, this book focuses on root cause of heat in embedded systems: power. Since software has an enormous impact on power consumption in an embedded system, this book urges software engineers to manage heat effectively by understanding, categorizing and developing new ways to reduce static and dynamic power consumption. Whereas most books on thermal management describe mechanisms to remove heat, this book focuses on ways for software engineers to avoid generating heat in the first place.
Soeleman, H., Roy, K.: Ultra-low power digital subthreshold logic circuits. Proceedings of the 1999 International Symposium on Low Power Electronics and Design, pp. 94–96. ACM, New York (1999) 19. Hemani, A., Meincke, T., Kumar, S., Postula, A., Olsson, T., Nilsson, P., Oberg, J., Ellervee, P., Lundqvist, D.: Lowering power consumption in clock by using globally asynchronous locally synchronous design style. Proceedings of the 36th ACM/IEEE Conference on Design automation 1999, pp. 873–878 (1999)
of a device over time . And, as we saw in the section on electronics (Sect. 3.3), embedded systems add compounding complications since they are small, usually in sealed enclosures, and are being built with faster clocks and increased computational complexity to meet the growing demands of consumer, industrial, and medical industries. Summary • The Law of Dynamic Power describes the fundamental relationship between power, frequency, and voltage. • To manage the thermal performance of an
Kindle Fire dynamic power curve (under computational load) is shown here. The Fire, while under high load using the ANTuTu Benchmark, exhibited the behavior we would expect based on our knowledge of the Law of Dynamic Power. Additionally, we observe that when both cores are running, both computational and power and thermal performance are better. DMIPS is used instead of MHz to standardize the x axis scale when comparing one versus two processor cores enabled, and the other with both cores
of power and thermal features supported by the hardware include Dynamic Voltage and Frequency Scaling (DVFS), Adaptive Voltage Scaling (AVS), Static Leakage Management (SLM), and Clock and Power Gating (CPG) features Fig. 5.2 Advanced Power Management (APM) and its successor Advanced Configuration and Power Interface (ACPI) attempt to standardize the way that power is managed on computing systems. APM put most of the power management logic into the BIOS (which many embedded systems do not have).
voltage and frequency settings, processor power domains, or peripheral interfaces and devices. In simple embedded systems, a Resource Manager could be a library. In high-level operating systems, a device driver framework may implement power or thermal management concepts. More information is included in the Resource Manager section (Sect. 5.2.1). 2. A Policy Manager for creating, executing, and responding to events in the system according to rules defined in the policies. An example policy might