Placement for Field Programmable Gate Arrays (FPGAs) is one of the most important but time-consuming steps for achieving design closure. This article proposes the integration of three unique machine learning models into the state-of-the-art analytic placement tool GPlace3.0 with the aim of significantly reducing placement runtimes. The first model, MLCong, is based on linear regression and replaces the computationally expensive global router currently used in GPlace3.0 to estimate switch-level congestion. The second model, DLManage, is a convolutional encoder-decoder that uses heat maps based on the switch-level congestion estimates produced by MLCong to dynamically determine the amount of inflation to apply to each switch to resolve congestion. The third model, DLRoute, is a convolutional neural network that uses the previous heat maps to predict whether or not a placement solution is routable. Once a placement solution is determined to be routable, further optimization may be avoided, leading to improved runtimes. Experimental results obtained using 372 benchmarks provided by Xilinx Inc. show that when all three models are integrated into GPlace3.0, placement runtimes decrease by an average of 48%.

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Optimizing for routability during FPGA placement is becoming increasingly important, as failure to spread and resolve congestion hotspots throughout the chip, especially in the case of large designs, may result in placements that either cannot be routed or that require the router to work excessively hard to obtain success. In this article, we introduce a new, analytic routability-aware placement algorithm for Xilinx UltraScale FPGA architectures. The proposed algorithm, called GPlace3.0, seeks to optimize both wirelength and routability. Our work contains several unique features including a novel window-based procedure for satisfying legality constraints in lieu of packing, an accurate congestion estimation method based on modifications to the pathfinder global router, and a novel detailed placement algorithm that optimizes both wirelength and external pin count. Experimental results show that compared to the top three winners at the recent ISPD’16 FPGA placement contest, GPlace3.0 is able to achieve (on average) a 7.53%, 15.15%, and 33.50% reduction in routed wirelength, respectively, while requiring less overall runtime. As well, an additional 360 benchmarks were provided directly from Xilinx Inc. These benchmarks were used to compare GPlace3.0 to the most recently improved versions of the first- and second-place contest winners. Subsequent experimental results show that GPlace3.0 is able to outperform the improved placers in a variety of areas including number of best solutions found, fewest number of benchmarks that cannot be routed, runtime required to perform placement, and runtime required to perform routing.

IntroductionA wide assortment of string similarity measures can be used to determine how similar two names are. A diverse set of discriminating and independent features for name similarity are important for classification during record linkage. A Siamese neural network could surpass traditional string similarity measures for the name similarity problem. Objectives and ApproachThis research aims to compare a classifier based on the Siamese network architecture with a Random Forest classifier. In addition to comparing overall performance, we seek to answer whether there are any special properties of certain matching name pairs where the complexity of the Siamese network offers particular benefit. Our data consists of 25,000 last name pairings, with each pair being two variants of a family name. Name similarity predictions from the Siamese network are compared to a Random Forest model that serves as an ensemble of existing string similarity measures. ResultsWe compare the similarity scores yielded by the two methods and discuss the results. We describe the representation of names to each method; name representation is computed formulaically for the traditional measures but is learned by the Siamese network during training. The comparison of different methods is made both in terms of their similarity prediction quality, and the computational cost to generate the predictions. As expected, the Siamese network necessitates a significant computational cost to train. Unexpectedly, the ensemble of traditional measures yields almost identical overall classification performance. However, we expect that further analysis of false positives and false negatives will yield some insight into when practitioners should consider one method over the other. Conclusions/ImplicationsResults suggest that there may be instances where a Siamese network outperforms other similarity measures, although training a Siamese network comes at a considerable computational cost. It is worth considering this approach to name similarity as an additional similarity feature when performing record linkage tasks.