Thermal Management of Reconfigurable Hardware(In Reverse Chronological Order)
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Abstract: This paper extends the previous work by additionally making this adaptive frequency mechanism workload aware and evaluating power and latency performance under bursty workload conditions. Our working system has been implemented on the Field Programmable Port Extender (FPX) platform developed at Washington University in St. Louis. Experimental results with a scalable image correlation circuit show up to a 30% saving in power for bursty workloads and up to a 2x factor improvement in latency performance as compared to a system without thermal or workload feedback. Our circuit provides power efficient high performance processing of bursty workloads, while ensuring the device always operates within a safe temperature range.
Abstract: High performance applications implemented with FPGAs can generate more heat than what their package can dissipate. This article overviews thermal results obtained from programming applications into a Xilinx Virtex FPGA. It also describes how a thermally adaptive computational mechanism was implemented that modulates the frequency to an FPGA circuit as a function of the temperature of the device. Both simple benchmark circuits and a more complex image processing circuit were implemented.
Abstract: Reconfigurable circuits running in Field Programmable Gate Arrays (FPGAs) can be dynamically optimized for power based on computational requirements and thermal conditions of the environment. In the past, FPGA circuits were typically small and operated at a low frequency. Few users were concerned about high-power consumption and the heat generated by FPGA devices. The current generation of FPGAs, however, use extensive pipelining techniques to achieve high data processing rates and dense layouts that can generate significant amounts of heat. FPGA circuits can be synthesized that can generate more heat than the package can dissipate. For FPGAs that operate in controlled environments, heatsinks and fans can be mounted to the device to extract heat from the device. When FPGA devices do not operate in a controlled environment, however, changes to ambient temperature due to factors such as the failure of a fan or a reconfiguration of bitfile running on the device can drastically change the operating conditions. A protection mechanism is needed to ensure the proper operation of the FPGA circuits when such a change occurs. To address these issues, we have devised a reconfigurable temperature monitoring system that gives feedback to the FPGA circuit using the measured junction temperature of the device. Using this feedback, we designed a novel dual frequency switching system that allows the FPGA circuits to maintain the highest level of performance for a given maximum junction temperature. Our working system has been implemented and deployed on the Field Programmable Port Extender (FPX) platform at Washington University in St. Louis. Our experimental results with a scalable image correlation circuit show up to a 2.4x factor increase in performance as compared to a system without thermal feedback. Our circuit ensures that the device performs the maximum required computation while always operating within a safe temperature range.
Abstract: Given large circuit sizes, high clock frequencies, and possibly extreme operating environments, Field Programmable Gate Arrays (FPGAs) are capable of heating beyond their designed thermal limits. As new circuits are developed for FPGAs and deployed remotely, engineers are challenged to determine in advance if the device will operate within recommended thermal ranges. The amount of power consumed by the circuit depends on how an algorithm is compiled into hardware, how the circuit is placed and routed, and the patterns of data that pass through the system. The amount of heat that can be dissipated depends on the thermal transfer characteristics of the package, the air flow that passes over the package, and the ambient temperature of the remote systems. Rather than designing a system to handle unreasonable worst-case situations, we have implemented a thermal management system that continuously monitors the temperature of the FPGA and reprograms the device if the temperate approaches the outer limits of safe operating conditions. Our system measures the junction temperature of a Xilinx Virtex FPGA using a built-in thermal diode. Using the temperature monitoring mechanism, we have studied the steady-state and transient conditions of multiple benchmark circuits implemented in an FPGA logic on the Field-programmable Port Extender (FPX) development platform. We observed properties of these benchmark circuits that enable us to predict power and thermal characteristics for real applications. We propose a Dynamic Thermal Management (DTM) strategy for FPGAs based on temperature feedback.