Thermal testing on reconfigurable computers

Univ. Autonoma de Madrid
IEEE Design and Test of Computers (Impact Factor: 1.62). 02/2000; DOI: 10.1109/54.825679
Source: DBLP

ABSTRACT Ring-oscillators are useful to monitor the thermal status of
reconfigurable computers. No analog parts exist, and the sensors can be
dynamically inserted, moved, or eliminated

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    ABSTRACT: In this paper, some experiments about thermal sensors based on ring-oscillator in low-voltage Virtex series FPGAs are presented. A non linear effect in the frequency-temperature response has been detected, and the sensibility of frequency with respect to voltage variations is greater than the measured in previous works. A quadratic polynomial function fits better the sensor response, and an increment in the number of inverters in the oscillator is effective to reduce the voltage sensibility.
    Programmable Logic Conference (SPL), 2010 VI Southern; 04/2010
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    ABSTRACT: This paper proposes a benchmarking methodology for characterising the power consumption of the fine-grain fabric in reconfigurable architectures. This methodology is part of the GroundHog 2009 power benchmarking suite. It covers active and inactive power as well as advanced low-power modes. A method based on random number generators is adopted for comparing activity modes. We illustrate our approach using five field-programmable gate arrays (FPGAs) that span a range of process technologies: Xilinx Virtex-II Pro, Spartan-3E, Spartan-3AN, Virtex-5, and Silicon Blue iCE65. We find that, despite improvements through process technology and low-power modes, current devices need further improvements to be sufficiently power efficient for mobile applications. The Silicon Blue device demonstrates that performance can be traded off to achieve lower leakage.
    International Journal of Reconfigurable Computing 01/2010;
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    ABSTRACT: Thermal issues have resulted in growing concerns among industries fabricating various types of devices, such as Chip Multiprocessors (CMP) and reconfigurable hardware devices. Since passive cooling costs have risen considerably and packaging for worst-case is no longer practical, dynamic thermal management techniques are being devised to combat thermal effects. For such techniques to be applied effectively, it is necessary to accurately measure device temperatures at run time. Although several techniques have been proposed to measure the on-chip temperatures of reconfigurable devices, ring oscillators in many ways are a preferred choice due to their strong linear temperature-dependence and compact design using available spare reconfigurable resources. A major problem in using ring-oscillators to measure temperature, however, is their strong dependence on the core voltage of, and current distribution throughout the device under test. One of the reasons for variations in these properties is changes in the workload running on the device. Researchers have seen large shifts in the output frequencies of ring-oscillators due to core voltage swings on reconfigurable devices, and have tried to find alternate ways of measuring temperature that attempt to mitigate these effects. The need, however, is to have a workload-compensated ring oscillator-based thermometer for reconfigurable devices. To obtain this, it is first necessary to characterize the non-ideal effects of workload variations on ring oscillator response. Where non-ideal refers to impacts on ring oscillator oscillation frequency due to phenomena other than the workload's impact on device temperature. This paper performs such a characterization, in which the effects of workload variation on ring oscillator output frequency is quantified. A complete hardware-software setup is designed to collect temperature and power related data along with ring oscillator response to varying workload configurations. In addition, a potential issue with using the Xilinx System Monitor to measure die temperature at high ranges is also briefly discussed.
    2011 International Conference on Reconfigurable Computing and FPGAs, ReConFig 2011, Cancun, Mexico, November 30 - December 2, 2011; 01/2011


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