Faculty Publications
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Item Study on heuristic approaches for symmetric traveling salesman problem(Nova Science Publishers, Inc., 2020) Yelmewad, P.; Talawar, B.Traveling Salesman Problem (TSP) is an NP-Hard class of combinatorial optimization problem. Getting an optimal solution for a large-scale TSP instance consumes infeasible time over the computational platform. Exact methods become intractable while solving large-scale TSP instances. Therefore, heuristic approaches are being used, which finds a satisfactory solution instead of an optimal solution in a reasonable time. The heuristic approach prohibits exploring all feasible solutions possible with exact methods; instead, either start with a random solution or construct a feasible solution following the specific criteria. This chapter presents the hybrid of improvement and construction heuristics, which produces a better cost-quality solution in lesser time. In the worst case, it creates a 1.91, 2.86 times better cost-quality compared to the improvement and construction heuristics, respectively. Moreover, it also provides the final cost in the least time, i.e., 16.51, 4.72 times faster than the improvement and construction heuristics, respectively. © 2020 Nova Science Publishers, Inc. All rights reserved.Item Nonvolatile Memory Technologies: Characteristics, Deployment, and Research Challenges(Springer International Publishing, 2023) Rai, S.; Talawar, B.Nonvolatile memory (NVM) is a class of memory that exhibits persistence, similar to secondary memory, while providing access speeds at least an order of two magnitudes faster. In this area, phase change memory (PCM), spin-transfer torque random access memory (STT-RAM), and resistive RAM (ReRAM) have emerged as the major contenders for commercial and industrial use. With the enormous amount of data being generated, most recent applications demand huge memory footprints, large bandwidth, low energy consumption, and low price. Conventional DRAM-based memories face several issues, such as scalability and high static power consumption. Hence there is a necessity to build alternative memory devices to satisfy the demands of new applications. In this regard, NVMs are gaining prominence these days. This chapter gives a complete overview of the NVM devices, including characteristics, deployment, and challenges in integrating them at different levels of the memory hierarchy. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023.Item On the Cache Behavior of SPLASH-2 Benchmarks on ARM and ALPHA Processors in Gem5 Full System Simulator(Institute of Electrical and Electronics Engineers Inc., 2014) Vikas, B.; Talawar, B.Today cache size and hierarchy level of caches play an important role in improving computer performance. By using full system simulations of gem5, the variation in memory bandwidth, system bus throughput, L1 and L2 cache size misses are measured by running SPLASH-2 Benchmarks on ARM and ALPHA Processors. In this work we calculate cache misses, memory bandwidth and system bus throughput by running SPLASH2 benchmarks on gem5 Full System Mode. Our results show that L1 cache misses decrease as L1 cache size is varied from 16KB to 64KB. L1 cache misses are independent of L2 cache size after the program data resides in L2 cache. The memory bandwidth and system bus throughput decreases as L1 and L2 cache size increases. © 2014 IEEE.Item A Crossbar Interconnection Network in DNA(Institute of Electrical and Electronics Engineers Inc., 2015) Talawar, B.DNA computers provide exciting challenges and opportunities in the fields of computer architecture, neural networks, autonomous micromechanical devices, and chemical reaction networks. The advent of digital abstractions such as the seesaw gates hold many opportunities for computer architects to realize complex digital circuits using DNA strand displacement principles. The paper presents a realization of a single bit, 2×2 crossbar interconnection network built using seesaw gates. The functional correctness of the implemented crossbar was verified using a chemical reaction simulator. © 2015 IEEE.Item Analysis of ring topology for NoC architecture(Institute of Electrical and Electronics Engineers Inc., 2016) Kamath, A.; Saxena, G.; Talawar, B.In recent years, Network on Chips (NoCs) have provided an efficient solution for interconnecting various heterogeneous intellectual properties (IPs) on a System on Chip (SoC) in an efficient, flexible and scalable manner. Virtual channels in the buffers associated with the core helps in introducing the parallelism between the packets as well as in improving the performance of the network. However, allocating a uniform size of the buffer to these channels is not always suitable. The network efficiency can be improved by allocating the buffer variably based on the traffic patterns and the node requirements. In this paper, we use ring topology as an underlying architecture for the NoC. The percentage of packet drops has been used as a parameter for comparing the performance of different architectures. Through the results of the simulations carried out in SystemC, we illustrate the impact of including virtual channels and variable buffers on the network performance. As per our results, we observed that varied buffer allocation led to a better performance and fairness in the network as compared to that of the uniform allocation. © 2015 IEEE.Item Cache analysis and software optimizations for faster on-chip network simulations(Institute of Electrical and Electronics Engineers Inc., 2016) Parane, K.; Prabhu Prasad, B.M.; Talawar, B.Fast simulations are critical in reducing time to market in CMPs and SoCs. Several simulators have been used to evaluate the performance and power consumed by Network-on-Chips. Researchers and designers rely upon these simulators for design space exploration of NoC architectures. Our experiments show that simulating large NoC topologies take hours to several days for completion. To speedup the simulations, it is necessary to investigate and optimize the hotspots in simulator source code. Among several simulators available, we choose Booksim2.0, as it is being extensively used in the NoC community. In this paper, we analyze the cache and memory system behaviour of Booksim2.0 to accurately monitor input dependent performance bottlenecks. Our measurements show that cache and memory usage patterns vary widely based on the input parameters given to Booksim2.0. Based on these measurements, the cache configuration having least misses has been identified. We also employ thread parallelization and vectorization to improve the overall performance of Booksim2.0. The OpenMP programming model and SIMD are used for parallelizing and vectorizing the more time-consuming portions of Booksim2.0. Speedups of 2.93× and 3.97× were observed for the Mesh topology with 30 × 30 network size by employing thread parallelization and vectorization respectively. © 2016 IEEE.Item YaNoC: Yet another network-on-chip simulation acceleration engine using FPGAS(IEEE Computer Society help@computer.org, 2018) Parane, K.; Talawar, B.; Prabhu Prasad, P.In this paper, we present an FPGA based NoC simulation framework, YaNoC, that supports the creation of standard and custom topologies, design of routing algorithms, generation of various synthetic traffic patterns, and exploration of a full set of microarchitectural parameters. The framework supports all standard minimal routing algorithms for conventional NoCs and implements table based routing to support the creation of new routing algorithm. A custom topology called Diagonal Mesh (DMesh) has been evaluated using table based and a modified version of the XY routing algorithm. Mesh and DMesh topologies saturate at the injection rates of 45 % and 55 %. We find that the Table based routing implementation consumes 0.98× fewer hardware resources than the conventional XY routing. We observed the speedup of 2548× compared to the Booksim software simulator. YaNoC achieves speedup of 2.54× and 25× with respect to CONNECT and DART FPGA based NoC simulators. © 2018 IEEE.Item Floorplan based performance evaluation of 3d variants of mesh and BFT networks-on-chip(Institute of Electrical and Electronics Engineers Inc., 2018) Halavar, B.; Talawar, B.Network on Chips(NoC) emerged as the reliable communication framework in CMPs and SoCs which enables in increase the number and complexity of cores. Many 2-D NoC architectures have been proposed for efficient on-chip communication. Cycle accurate simulators model the functionality and behavior of NoCs by considering micro-architectural parameters of the underlined components to estimate performance metric. Using 3D IC technology in NoC can lead to improved communication latency and power compared to their 2D counterpart with use of through-silicon via (TSVs) as vertical interconnect. In this paper, we explore the design space of 3D variants of the Mesh and Butterfly Fat Tree(BFT) NoCs using floorplan driven wire and TSV lengths. Analysed the performance of 2D and 3D variants of the Mesh and BFT topologies by injecting uniform traffic pattern. Results of our experiments show that, average network latency of a 4-layer 3D Mesh shows better on-chip communication performance compare to other 3D variants. In 4-layer 3D Mesh, on-chip communication performance is improved up to 2.2× compare to 2D Mesh and 4.5× compare to 4-layer 3D BFT. © 2018 IEEE.Item Thermal Aware Design for Through-Silicon Via (TSV) based 3D Network-on-Chip (NoC) Architectures(Institute of Electrical and Electronics Engineers Inc., 2018) Pasupulety, U.; Halavar, B.; Talawar, B.Through-Silicon Vias(TSVs) are a type of on-chip interconnect used for communication between multiple layers of circuit elements in a 3D IC. Multiple TSVs form a vertical link connecting inter-layer elements in 3D Network-on-Chip(NoC) architectures. Microarchitectural parameters such as length, width, pitch, and operating frequency influence the total power consumed and heat dissipated by TSVs. Effective extraction of the heat between layers is a significant challenge in 3D NoCs. Modelling the power of the TSVs and the thermal profile of 3D NoCs accurately enable designers perform trade-off studies during the design phase. In this work, we evaluate the thermal behaviour of 2 layer 3D Mesh and CMesh NoC architectures. We extended HotSpot to provide support for the inclusion of a router-TSV circuit element as a part of the 3D NoC floorplan. For the 3D Mesh, the thermal behaviour was analyzed for the naive arrangement as well as a proposed thermally aware design of the router-TSV element. Additionally, the thermal effect of multiple cores sharing a single router-TSV in a CMesh architecture was investigated. Our experiments show that the average of the maximum temperatures of all the routers in the 4x8x2 thermal-aware 3D Mesh is lowered by 3% compared to the naive 3D Mesh design. Also, the average of the maximum temperatures of all the routers in a 3D CMesh is 7% more than the naive 3D Mesh and 9% more than the thermally aware 3D Mesh design. © 2018 IEEE.Item Trace-Driven Simulation and Design Space Exploration of Network-on-Chip Topologies on FPGA(Institute of Electrical and Electronics Engineers Inc., 2018) Sangeetha, G.S.; Radhakrishnan, V.; Prabhu Prasad, P.; Parane, K.; Talawar, B.Networking On Chips is now becoming an extremely important part of the present and future of electronic technology. It is extensively used in Multiprocessor System-on-Chips and in Chip Multiprocessors. Using an NoC, the backend wiring involved has drastically reduced in an SoC. Further, SoCs with NoC interconnect operates at a higher operating frequency, mainly because the hardware required for switching and routing are simplified. The NoC researchers have relied on simulators based on performance and power to study the different factors of NoC such as algorithm in place, the topology, the buffer management and location schemes, the flow control and routing among others. In this paper, we present a trace-driven NoC architecture that gives the user access to realistic details about the resource utilization of NoC architectures and their individual components. This includes exploration of various design decision parameters of NoC by modeling them on a FPGA. The paper also presents the performance of these architectures by conducting trace-driven simulations using benchmarks like PARSEC. Different topologies are considered for experimentation purposes with different routing algorithms. © 2018 IEEE.